An automatic testing method for LCD surface force

Abstract

This invention provides an automatic testing method for the surface forces of an LCD, comprising: fixing the LCD under test on a test platform to complete the reference positioning of the LCD under test; installing the suction ball under test on the adsorption actuator to complete the vertical alignment of the suction ball and the surface of the LCD under test, and preset test action parameters; controlling the suction ball under test through the adsorption actuator to perform a complete action cycle of squeezing-adsorption-pressure holding-release on the surface of the LCD under test; synchronously collecting the real-time state parameters of the suction ball under test and the real-time deformation parameters of the LCD under test; based on the collected real-time state parameters and real-time deformation parameters, quantitatively calculating the real-time forces and real-time deformations on the surface of the LCD under test; comparing the calculated real-time forces and real-time deformations with preset thresholds, and outputting the final test results; this invention aims to achieve accurate quantitative calculation of the normal force, shear force, and deformation of the LCD surface during the suction ball adsorption process, providing a quantitative basis for suction ball selection and use.

Description

Technical Field

[0001] This invention relates to the field of display device manufacturing technology, and in particular to an automatic testing method for surface forces on LCDs. Background Technology

[0002] In the field of display device manufacturing, LCD is the mainstream display panel. The refinement and automation of its production process have continued to improve with the development of display technology. From the early TN LCD to today's IPS and VA high-performance LCD, the trend of thinner and more refined panels is obvious. IPS screens have become mainstream products due to their wide viewing angle and high color reproduction. However, their glass substrates are thinner and their internal liquid crystal arrangement is more sensitive to external stress. Even small surface forces or deformations can cause abnormal panel display, which has become a key difficulty in process control. In the process of picking up and handling LCDs, rubber suction balls have become the core operating component to avoid contamination and damage caused by manual contact. They achieve adsorption by creating negative pressure through compression and rebound. This technology has evolved from early manual suction balls to automated adsorption and handling in conjunction with robotic arms. The material and structure of the suction balls have also been continuously optimized, upgrading from ordinary rubber balls to wear-resistant and low-deformation silicone suction balls. However, there has always been a technological gap in the core testing process for the use of suction balls in the industry. Specifically, there is a lack of quantitative testing methods for the adsorption force, shear force, and panel deformation generated by the suction balls adsorbing onto the LCD surface. For a long time, the suitability of the suction balls has been judged by the sensory experience of operators, without a unified quantitative standard. In existing technologies, some companies only test the negative pressure inside the suction ball cavity using simple pressure gauges. This fails to comprehensively calculate the total force caused by the elastic recovery force of the rubber and the interface adhesion force, and it also fails to test the actual deformation and shear stress of the LCD surface. At the same time, the lack of a standardized suction ball operation cycle test process leads to a disconnect between test data and actual working conditions. As a result, some suction balls, although meeting the negative pressure standard, exert force or deformation on the IPS screen beyond the tolerance range during actual use, causing defects such as dark spots and bright lines on the panel, increasing production losses. Furthermore, the lack of unified quantitative testing standards for suction balls of different batches and specifications makes it difficult to achieve standardized screening and use of suction balls, thus restricting the improvement of LCD production yield. Therefore, there is an urgent need in the field for an automatic testing method for the surface forces of LCDs to solve the above problems. Summary of the Invention

[0003] This invention provides an automatic testing method for the surface forces of an LCD, aiming to solve the technical problem that the force and deformation of the suction ball on the panel surface cannot be quantified in LCD manufacturing and are judged solely by sensory perception. It provides a standardized and automated testing method to achieve accurate quantitative calculation of the normal force, shear force, and deformation of the LCD surface during the suction ball adsorption process, providing a quantitative basis for the selection and use of suction balls.

[0004] This invention provides an automatic testing method for the surface forces of an LCD, comprising the following steps: S1. Fix the LCD under test on the test platform to complete the reference positioning of the LCD under test; S2. Install the suction ball to be tested onto the adsorption actuator, complete the vertical alignment of the suction ball with the surface of the LCD to be tested, and preset the test action parameters; S3. The suction ball under test is controlled by the adsorption actuator to perform a complete cycle of squeezing-adsorption-pressure holding-release on the LCD surface under test. S4. During the entire process of the complete action cycle, the real-time status parameters of the suction ball under test and the real-time deformation parameters of the LCD under test are collected simultaneously. S5. Based on the collected real-time state parameters and real-time deformation parameters, the real-time force and real-time deformation of the LCD surface under test are quantitatively calculated. S6. Compare the calculated real-time force and real-time deformation with the preset LCD tolerance threshold and output the final test results.

[0005] Compared with the prior art, the beneficial effects of this application are as follows: 1. This application establishes a complete standardized testing process, from LCD fixed positioning and ball alignment parameter preset, to simulating the actual working conditions of the squeezing-adsorption-pressure holding-release action cycle, and then to parameter acquisition, quantitative calculation and result judgment, forming a closed-loop testing system. The testing process is highly consistent with the actual production working conditions, and the data reference is stronger.

[0006] 2. This application innovatively designs a quantitative calculation model of multi-force superposition, which decomposes the total force into vacuum pressure difference adsorption force, rubber elastic recovery force and interface adsorption force. Combined with leakage correction and large deformation nonlinear correction, it realizes accurate calculation of normal force. At the same time, it supplements the quantification of shear force and shear stress, filling the gap in the industry for full-dimensional quantification of suction ball force.

[0007] 3. Based on the thin plate bending theory of elasticity, this application simplifies the LCD into a simply supported circular thin plate. Combined with boundary constraint correction, the maximum deformation of the adsorption area is calculated, which accurately matches the screen's sensitivity to deformation, realizes the quantitative determination of deformation, and effectively avoids panel defects caused by excessive deformation.

[0008] 4. This application also includes system calibration and repeatability verification steps. By calibrating the acquisition unit with standard instruments and calculating the relative standard deviation of the test data to verify its effectiveness, the accuracy and repeatability of the test data are guaranteed, providing a unified quantitative basis for the standardized screening and batch testing of suction bulbs.

[0009] 5. This application automates the testing process and visualizes the data output. It simultaneously collects multi-dimensional parameters and automatically generates curves for force, deformation, etc. Combined with three-level judgment criteria, it outputs qualified, unqualified, or warning results, replacing the traditional manual sensory judgment, improving the testing efficiency. At the same time, the stored test data can be traced and analyzed, providing data support for the optimization of the suction ball structure and the adjustment of LCD process parameters, effectively reducing panel loss in LCD production, and improving the overall production yield and process stability.

[0010] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0011] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof; in the drawings: Figure 1 This is a flowchart illustrating an automatic testing method for the surface forces of an LCD provided by the present invention. Detailed Implementation

[0012] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Example 1:

[0013] This invention provides an automatic testing method for the surface forces of an LCD. Please refer to [link / reference]. Figure 1 This includes the following steps: S1. Fix the LCD under test on the test platform to complete the reference positioning of the LCD under test; S2. Install the suction ball to be tested onto the adsorption actuator, complete the vertical alignment of the suction ball with the surface of the LCD to be tested, and preset the test action parameters; S3. The suction ball under test is controlled by the adsorption actuator to perform a complete cycle of squeezing-adsorption-pressure holding-release on the LCD surface under test. S4. During the entire complete action cycle, the real-time status parameters of the suction ball under test and the real-time deformation parameters of the LCD under test are collected simultaneously. S5. Based on the collected real-time state parameters and real-time deformation parameters, the real-time force and real-time deformation of the LCD surface under test are quantitatively calculated. S6. Compare the calculated real-time force and real-time deformation with the preset LCD tolerance threshold and output the final test results.

[0014] Specifically, this embodiment controls the suction ball to complete a standard action cycle of adhesion and adsorption by fixing and positioning the LCD under test, installing and aligning the suction ball under test, and setting parameters. Simultaneously, relevant parameters of the suction ball state and LCD deformation are collected. Based on the parameters, the force and deformation on the LCD surface are quantitatively calculated. Finally, the test result is determined by comparing with the preset tolerance threshold. This realizes the quantitative testing of the force and deformation of the suction ball on the LCD surface, solving the technical problem of relying solely on sensory judgment in the industry. The overall steps form a complete test closed loop.

[0015] In one implementation, step S1 includes: S11. Place the LCD to be tested horizontally on the support position of the test platform, and fix the non-test surface of the LCD to be tested to the test platform through the vacuum adsorption channel; S12. The edge features of the LCD under test are collected by the machine vision positioning unit. Based on the preset reference coordinates, the XY axis displacement of the test platform is adjusted to complete the reference positioning of the LCD under test. S13. Use a laser level to calibrate the levelness of the test surface of the LCD under test, ensuring that the angle between the test surface and the horizontal plane is less than the preset angle.

[0016] Specifically, in this embodiment, the non-test surface of the LCD under test is first fixed to the support position of the test platform using vacuum adsorption to ensure that the LCD does not shift during the test. Then, a machine vision positioning unit is used to identify the edge features of the LCD, and the XY axes of the test platform are adjusted in conjunction with preset reference coordinates to achieve precise reference positioning of the LCD and ensure the consistency of the test position. Finally, a laser level is used to calibrate the levelness of the LCD test surface, controlling the angle between the test surface and the horizontal plane within a preset angle to avoid deviations in the suction force and deformation acquisition caused by LCD tilt, thus providing a foundation for the accurate execution of subsequent test actions. The machine vision positioning unit and the laser level are existing technologies and will not be described in detail in this embodiment.

[0017] In one implementation, step S2 includes: S21. Coaxially install the suction ball to be tested onto the end clamp of the adsorption actuator, and enter the inherent parameters of the suction ball to be tested, including the nominal diameter of the ball disk, the thickness of the ball lip, the elastic modulus of the rubber material, Poisson's ratio, and the initial inner cavity volume. S22. The relative position of the suction ball plate and the LCD surface to be tested is collected by the machine vision alignment unit. The XYZ axis displacement and rotation angle of the adsorption actuator are adjusted so that the central axis of the suction ball plate is perpendicularly aligned with the LCD surface to be tested. S23. Preset test action parameters, including suction and squeezing stroke, squeezing speed, pressure holding time, release speed, and number of test cycles.

[0018] Specifically, in this embodiment, the suction ball to be tested is first coaxially mounted on the end fixture of the adsorption actuator. At the same time, the inherent material and structural parameters of the suction ball, such as the nominal diameter of the ball disk and the thickness of the ball lip, are recorded. The values ​​of each parameter can be obtained by existing means and are used to provide basic data for subsequent calculation of force and deformation. The relative position of the suction ball disk and the LCD surface to be tested is obtained by the machine vision alignment unit (existing means). The XYZ axis displacement and rotation angle of the adsorption actuator are adjusted to achieve perpendicular alignment between the central axis of the suction ball disk and the LCD surface to be tested, ensuring that the suction force acts perpendicularly on the LCD surface and avoiding shear force interference. Finally, the extrusion stroke, extrusion speed and other test action parameters are preset to achieve standardized control of the suction ball test action and ensure the repeatability of the test.

[0019] In one implementation, step S3 includes: S31, Extrusion Stage: Control the adsorption actuator to move the suction ball to be tested toward the surface of the LCD to be tested at a preset extrusion speed until the preset extrusion stroke is reached, so that the lip of the suction ball is completely attached to the surface of the LCD to be tested, forming a sealed cavity. S32, Adsorption stage: Control the adsorption actuator to stop displacement, release the squeezing constraint of the suction ball to be tested, and let the suction ball recover by its own rubber elasticity, forming a negative pressure in the sealed cavity to complete the adsorption of the LCD surface to be tested. S33, Pressure Holding Stage: Keep the position of the adsorption actuator fixed so that the adsorption state of the test ball on the test LCD is maintained for a preset pressure holding time; S34. Release phase: Control the adsorption actuator to move the suction ball away from the LCD to be tested, and release the contact between the suction ball and the surface of the LCD to be tested at a preset release speed, completing a single action cycle.

[0020] Specifically, this embodiment divides the action into four stages: squeezing, adsorption, pressure holding, and release, simulating the actual process of a suction ball transporting an LCD. In the squeezing stage, the adsorption actuator drives the suction ball towards the LCD according to preset parameters, causing the ball lip to adhere to the LCD surface to form a sealed cavity, providing a basis for adsorption. In the adsorption stage, the squeezing constraint of the suction ball is released, and the elastic recovery characteristics of rubber create negative pressure within the sealed cavity, achieving adsorption of the LCD by the suction ball, replicating the actual adsorption principle. In the pressure holding stage, the adsorption state is maintained for a preset duration, simulating the holding process of the suction ball transporting the LCD. In the release stage, the suction ball is moved away from the LCD at a preset speed, releasing contact and completing a single cycle. This standardized action cycle ensures the consistency between the test data and actual working conditions. It should be noted that each preset value can be manually set in actual applications; this embodiment does not impose any restrictions.

[0021] In one implementation, step S4 specifically includes: S41. Use the start signal of the action cycle as the synchronous trigger signal and set a uniform sampling frequency; S42. The absolute pressure inside the sealed cavity of the suction ball under test is collected in real time by a vacuum sensor installed at the end of the adsorption actuator. The real-time deformation of the suction bulb under test is collected by a displacement sensor. The actual effective contact diameter between the suction ball and the surface of the LCD under test is collected in real time using a high-speed vision sensor. ; S43. Real-time acquisition of normal displacement data at multiple points on the surface of the LCD under test using a laser displacement sensor array; real-time acquisition of the triaxial acceleration of the adsorption actuator using a triaxial accelerometer. ; S44. Perform timestamp synchronization and low-pass filtering preprocessing on all collected parameters to remove high-frequency noise interference and obtain synchronized real-time status parameters and real-time deformation parameters.

[0022] Specifically, in this embodiment, the action cycle start signal is first used as the synchronous trigger signal and a uniform sampling frequency is set to ensure the time synchronization of all parameter acquisitions; then, the absolute pressure of the suction ball sealing cavity is collected by a vacuum sensor, a displacement sensor, and a high-speed vision sensor, respectively. Real-time deformation of the suction ball Actual effective contact diameter of the suction ball and LCD Real-time status parameters of the suction ball are collected by a laser displacement sensor array and a triaxial accelerometer, respectively, to obtain multi-point normal displacement data of the LCD test surface and triaxial acceleration data of the adsorption actuator. Real-time deformation parameters of the LCD are collected to achieve comprehensive acquisition of key parameters during the testing process. Finally, all collected parameters are preprocessed with timestamp synchronization and low-pass filtering to eliminate high-frequency noise interference, resulting in accurate and synchronized real-time state and deformation parameters, providing a reliable data foundation for subsequent quantitative calculations. The principles of the data acquired using vacuum sensors, displacement sensors, high-speed vision sensors, laser displacement sensor arrays, and triaxial accelerometers are existing methods and will not be elaborated upon in this embodiment.

[0023] In one implementation, step S5, the process of quantifying and calculating the real-time force acting on the surface of the LCD to be tested, includes: Real-time force Adsorption force due to vacuum pressure difference Rubber elastic recovery force With interfacial adsorption force The result is obtained by superimposing the three parts, and the calculation formula is: ; Among them, vacuum pressure difference adsorption force for: ; In the formula, Standard atmospheric pressure Let be the real-time absolute pressure inside the suction bulb cavity at time t. Let be the real-time effective contact area between the suction ball and the LCD at time t. Aerodynamic viscosity, This is the length of the suction bulb leakage channel. Let be the real-time volume of the suction bulb's inner cavity at time t. The diameter of the suction ball leakage hole, The rate of change of the real-time deformation of the suction ball; rubber elastic recovery force The calculation formula is: ; In the formula, The elastic modulus of the suction ball rubber material. For the thickness of the suction ball lip, The Poisson's ratio of the suction rubber material. The initial extrusion deformation of the suction ball; Interfacial Adsorption The calculation formula is: ; In the formula, The interfacial energy between the suction ball rubber and the LCD surface. This refers to the balanced contact angle between the suction rubber and the LCD glass surface.

[0024] Specifically, Based on the principle of superposition of forces, that is, the total force acting on an object is equal to the vector sum of its components, and since all three forces are normal forces perpendicular to the LCD surface, they are directly superimposed algebraically; regarding parameters, Let t be the total normal force acting on the LCD surface at real time. The adsorption force generated by the vacuum pressure difference at time t. Let t be the force generated by the elastic recovery of the rubber at time t. The force is the interfacial adsorption force between the suction ball and the LCD surface at time t. All force parameters are obtained from the data collected in step S4 or the inherent parameters of the suction ball entered in step S2.

[0025] Vacuum pressure difference adsorption force formula Based on the principle of pressure difference force combined with leakage correction, the basic pressure difference force is the difference between standard atmospheric pressure and the real-time pressure inside the suction bulb cavity multiplied by the contact area. It also considers air leakage from the suction bulb's sealed cavity and pressure loss due to changes in the suction bulb's deformation. A correction term is used to calibrate the basic value, making the calculated value more closely reflect reality. In the formula... This is the fundamental term for vacuum pressure difference adsorption force under ideal, leak-free conditions. This is a correction term for pressure loss caused by leakage and deformation changes. The correction term is the calibration coefficient for the actual vacuum pressure difference adsorption force.

[0026] Rubber elastic restoring force formula The formula considers the large deformation characteristics and Poisson's ratio of rubber, and incorporates structural modifications such as lip thickness and contact diameter to achieve accurate calculation of the rubber's elastic restoring force; where This is the elastic coefficient determined by the rubber material and the suction ball structure. For the actual elastic deformation term of the suction ball, The nonlinear correction term for the large deformation of rubber compensates for the limitations of the classical Hooke's law for small deformations and adapts to the actual deformation of the suction ball rubber.

[0027] Interfacial Adsorption Force Formula Based on Young's equation and the principle of interfacial tension, when a solid comes into contact with a liquid / elastic, the adsorption force generated by the interface is related to the contact perimeter, the interfacial energy, and the cosine value of the contact angle. Let be the interfacial energy between the suction ball rubber and the LCD glass, and be a known intrinsic parameter of the material. Let be the equilibrium contact angle between the suction ball rubber and the LCD glass surface, and be a known material contact characteristic parameter; where ... This is the actual contact perimeter between the suction ball and the LCD surface. The interfacial adsorption force per unit contact perimeter is the force generated. The product of the two is the total interfacial adsorption force, which conforms to the calculation law of interfacial tension.

[0028] In one implementation, step S5, the process of quantifying and calculating the real-time deformation of the LCD surface to be measured, includes: The LCD under test is simplified as a thin circular plate with simple supports on all four sides, and the real-time maximum deformation at the center of the adsorption region of the LCD under test is calculated. The calculation formula is: ; In the formula, The bending stiffness of the LCD sheet to be tested. , The elastic modulus of LCD glass. For the thickness of the LCD glass, The Poisson's ratio of the LCD surface. The effective support radius of the LCD under test is denoted as .

[0029] Specifically, this embodiment considers that the LCD has a thin plate structure, and simplifies it into a circular thin plate with simple support on all four sides, that is, it conforms to the actual boundary conditions of the LCD being supported by the test platform. Based on the thin plate bending theory of elasticity, the real-time maximum deformation at the center of the adsorption region is calculated. (The deformation at the LCD adsorption point is greatest at the center, and this value is a key indicator for determining whether the LCD deformation exceeds the standard.)

[0030] Among them, the bending stiffness formula This is the classic formula for calculating the bending stiffness of thin plates, characterizing the ability of LCD glass to resist bending deformation. The greater the bending stiffness, the less prone the LCD is to bending deformation; among which, The elastic modulus of the LCD glass (is a known inherent parameter of the material and can be pre-entered). The thickness of the LCD glass (a structural parameter of the LCD to be tested, which can be pre-entered). The formula represents the Poisson's ratio of the LCD glass (a known inherent parameter of the material, which can be pre-entered); where... The core term for bending stiffness is determined by the LCD material and thickness, with thickness being a cubic term, demonstrating the significant impact of LCD thickness on its bending resistance. This is the theoretical correction factor for thin plate bending, used to eliminate the influence of lateral deformation caused by Poisson's ratio on bending stiffness.

[0031] Real-time maximum deformation formula For the case of a simply supported circular thin plate subjected to a uniformly distributed circular load at its center, the maximum deflection at the center of the plate (i.e., the maximum deformation of the LCD) is calculated analytically; where... This is the basic amplitude term for the maximum deformation at the center of the LCD. The greater the total force and the larger the contact diameter, the greater the basic deformation; conversely, the greater the bending stiffness, the smaller the basic deformation. This is the theoretical coefficient for a circular thin plate subjected to a central circular load; The boundary constraint correction term is a theoretical natural coefficient term derived through rigorous integration of the biharmonic equations of elasticity. This is a fundamental contribution to the bending deformation of the thin plate under a central circular load. This is a correction term for the simply supported boundaries around the LCD to offset the deformation at the center. The negative sign indicates that the boundary support weakens the deformation at the center. The higher-order correction term introduced by the boundary constraints adapts to the influence of the change in the ratio of the support radius to the contact diameter on the deformation. The combination of these three terms enables the accurate calculation of the maximum deformation under the actual boundary conditions of the LCD.

[0032] In one embodiment, step S5 further includes a process of quantifying and calculating the real-time shear force and maximum shear stress on the surface of the LCD to be tested, wherein the real-time shear force... The calculation formula is: ; In the formula, To assess the quality of the LCD under test, Let t be the horizontal acceleration of the adsorption actuator. The real-time static friction force between the suction ball and the LCD surface; Among them, the real-time maximum shear stress The calculation formula is: ; In the formula, The shear modulus of the suction ball rubber material. .

[0033] Specifically, this embodiment adds quantitative calculation of real-time shear force and maximum shear stress on the LCD surface, making up for the deficiency of only testing normal force and deformation. When the suction ball actually moves the LCD, there is horizontal movement and shear force, thus realizing the comprehensive quantification of the force on the LCD surface. Among them, the formula for rubber shear modulus Applicable to isotropic elastic materials, used to indirectly calculate the shear modulus of rubber, characterizing the rubber's ability to resist shear deformation; Real-time shear force formula Based on the superposition principle of Newton's second law and static friction, the shear force generated when the suction ball moves the LCD is mainly the sum of the inertial force that drives the LCD to move horizontally and the static friction between the suction ball and the LCD surface. The real-time static friction force between the suction ball and the LCD surface can be calculated using the material friction coefficient and normal pressure, where the friction coefficient is a known parameter; where, The inertial shear force generated by the horizontal acceleration of the LCD. The static shear force between the suction ball and the LCD surface is the sum of the static shear force between the two, which constitutes the real-time total shear force on the LCD surface.

[0034] Real-time maximum shear stress formula The shear stress is calculated based on the shear stress under uniformly distributed load, combined with material and structural corrections. The shear stress is calculated by dividing the shear force by the contact area. The difference in shear modulus between the suction ball rubber and the LCD glass, as well as the structural difference between the ball lip thickness and the LCD thickness, are considered to correct the base value, achieving accurate calculation of the shear stress. Where, The basic shear stress term for uniformly distributed shear force on a circular contact surface ( (where is the stress distribution coefficient of the circular surface). For material and structural modifications, among which The ratio of the material shear properties of the suction ball to that of the LCD is given. The thickness ratio of the LCD to the ball lip. The ratio of the spherical lip thickness to the contact diameter is used to combine various factors to eliminate the influence of material and structural differences on the shear stress calculation, making the calculated value more realistic.

[0035] In one implementation, step S6 includes: S61. Preset the force tolerance threshold, deformation tolerance threshold and shear stress tolerance threshold of the LCD to be tested; S62. Compare the calculated real-time peak force, real-time maximum deformation peak, and real-time maximum shear stress peak with their corresponding tolerance thresholds. S63. If all peak values ​​are less than or equal to the corresponding tolerance threshold, the test result is deemed qualified; if any peak value exceeds the corresponding tolerance threshold, the test result is deemed unqualified; if any peak value reaches more than 90% of the tolerance threshold, an early warning message is output. S64. Output and store the test results, including real-time force curve, deformation curve, shear stress curve, peak data and judgment results.

[0036] In one implementation, the system calibration step before testing and the repeatability verification step after testing are also included. The system calibration steps include: using standard weights to perform multi-point calibration of the force acquisition unit within its range, and using standard gauge blocks to perform accuracy calibration of the displacement acquisition unit; The repeatability verification steps include: repeating steps S3 to S6 according to the preset number of test cycles, calculating the relative standard deviation of the test results multiple times, and determining that the test data is valid if the relative standard deviation is less than the preset deviation; otherwise, retesting is performed.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic testing method for surface forces on an LCD, characterized in that, Includes the following steps: S1. Fix the LCD under test on the test platform to complete the reference positioning of the LCD under test; S2. Install the suction ball to be tested onto the adsorption actuator, complete the vertical alignment of the suction ball with the surface of the LCD to be tested, and preset the test action parameters; S3. The suction ball under test is controlled by the adsorption actuator to perform a complete cycle of squeezing-adsorption-pressure holding-release on the LCD surface under test. S4. During the entire process of the complete action cycle, the real-time status parameters of the suction ball under test and the real-time deformation parameters of the LCD under test are collected simultaneously. S5. Based on the collected real-time state parameters and real-time deformation parameters, the real-time force and real-time deformation of the LCD surface under test are quantitatively calculated. S6. Compare the calculated real-time force and real-time deformation with the preset LCD tolerance threshold and output the final test results.

2. The automatic testing method for surface forces on an LCD according to claim 1, characterized in that, Step S1 includes: S11. Place the LCD to be tested horizontally on the support position of the test platform, and fix the non-test surface of the LCD to be tested to the test platform through the vacuum adsorption channel; S12. The edge features of the LCD under test are collected by the machine vision positioning unit. Based on the preset reference coordinates, the XY axis displacement of the test platform is adjusted to complete the reference positioning of the LCD under test. S13. Use a laser level to calibrate the levelness of the test surface of the LCD under test, ensuring that the angle between the test surface and the horizontal plane is less than the preset angle.

3. The automatic testing method for LCD surface forces according to claim 1, characterized in that, Step S2 includes: S21. The suction ball to be tested is coaxially mounted on the end clamp of the adsorption actuator, and the inherent parameters of the suction ball to be tested are entered. The inherent parameters include the nominal diameter of the ball disk, the thickness of the ball lip, the elastic modulus of the rubber material, Poisson's ratio, and the initial inner cavity volume. S22. The relative position of the suction ball plate and the LCD surface to be tested is collected by the machine vision alignment unit. The XYZ axis displacement and rotation angle of the adsorption actuator are adjusted so that the central axis of the suction ball plate is perpendicularly aligned with the LCD surface to be tested. S23. Preset test action parameters, including suction and squeezing stroke, squeezing speed, pressure holding time, release speed, and number of test cycles.

4. The automatic testing method for surface forces on an LCD according to claim 1, characterized in that, Step S3 includes: S31, Extrusion Stage: Control the adsorption actuator to move the suction ball to be tested toward the surface of the LCD to be tested at a preset extrusion speed until the preset extrusion stroke is reached, so that the lip of the suction ball is completely attached to the surface of the LCD to be tested, forming a sealed cavity. S32, Adsorption stage: Control the adsorption actuator to stop displacement, release the squeezing constraint of the suction ball to be tested, and let the suction ball recover by its own rubber elasticity, forming a negative pressure in the sealed cavity to complete the adsorption of the LCD surface to be tested. S33, Pressure Holding Stage: Keep the position of the adsorption actuator fixed so that the adsorption state of the test ball on the test LCD is maintained for a preset pressure holding time; S34. Release phase: Control the adsorption actuator to move the suction ball away from the LCD to be tested, and release the contact between the suction ball and the surface of the LCD to be tested at a preset release speed, completing a single action cycle.

5. The automatic testing method for surface forces on an LCD according to claim 1, characterized in that, Step S4 specifically includes: S41. Use the start signal of the action cycle as the synchronous trigger signal and set a uniform sampling frequency; S42. The absolute pressure inside the sealed cavity of the suction ball under test is collected in real time by a vacuum sensor installed at the end of the adsorption actuator. The real-time deformation of the suction bulb under test is collected by a displacement sensor. The actual effective contact diameter between the suction ball and the surface of the LCD under test is collected in real time using a high-speed vision sensor. ; S43. Real-time acquisition of normal displacement data at multiple points on the surface of the LCD under test using a laser displacement sensor array; real-time acquisition of the triaxial acceleration of the adsorption actuator using a triaxial accelerometer. ; S44. Perform timestamp synchronization and low-pass filtering preprocessing on all collected parameters to remove high-frequency noise interference and obtain synchronized real-time status parameters and real-time deformation parameters.

6. The automatic testing method for LCD surface forces according to claim 1, characterized in that, In step S5, the process of quantifying and calculating the real-time force acting on the surface of the LCD to be tested includes: The real-time force Adsorption force due to vacuum pressure difference Rubber elastic recovery force With interfacial adsorption force The result is obtained by superimposing the three parts, and the calculation formula is: ； Wherein, the vacuum pressure difference adsorption force for: ； In the formula, Standard atmospheric pressure Let be the real-time absolute pressure inside the suction bulb cavity at time t. Let be the real-time effective contact area between the suction ball and the LCD at time t. Aerodynamic viscosity, This is the length of the suction bulb leakage channel. Let be the real-time volume of the suction bulb's inner cavity at time t. The diameter of the suction ball leakage hole, The rate of change of the real-time deformation of the suction ball; The elastic restoring force of the rubber The calculation formula is: ； In the formula, The elastic modulus of the suction ball rubber material. For the thickness of the suction ball lip, The Poisson's ratio of the suction rubber material. The initial extrusion deformation of the suction ball; The interfacial adsorption force The calculation formula is: ； In the formula, The interfacial energy between the suction ball rubber and the LCD surface. This refers to the balanced contact angle between the suction rubber and the LCD glass surface.

7. The automatic testing method for LCD surface forces according to claim 6, characterized in that, In step S5, the process of quantizing and calculating the real-time deformation of the LCD surface under test includes: The LCD under test is simplified as a thin circular plate with simple supports on all four sides, and the real-time maximum deformation at the center of the adsorption region of the LCD under test is calculated. The calculation formula is: ； In the formula, The bending stiffness of the LCD sheet to be tested. , The elastic modulus of LCD glass. For the thickness of the LCD glass, The Poisson's ratio of the LCD surface. The effective support radius of the LCD under test is denoted as .

8. The automatic testing method for surface forces on an LCD according to claim 7, characterized in that, Step S5 further includes a process of quantitatively calculating the real-time shear force and maximum shear stress on the surface of the LCD to be tested, wherein the real-time shear force... The calculation formula is: ； In the formula, To assess the quality of the LCD under test, Let t be the horizontal acceleration of the adsorption actuator. The real-time static friction force between the suction ball and the LCD surface; The real-time maximum shear stress The calculation formula is: ； In the formula, The shear modulus of the suction ball rubber material. .

9. The automatic testing method for surface forces on an LCD according to claim 1, characterized in that, Step S6 includes: S61. Preset the force tolerance threshold, deformation tolerance threshold and shear stress tolerance threshold of the LCD to be tested; S62. Compare the calculated real-time peak force, real-time maximum deformation peak, and real-time maximum shear stress peak with their corresponding tolerance thresholds. S63. If all peak values ​​are less than or equal to the corresponding tolerance threshold, the test result is deemed qualified; if any peak value exceeds the corresponding tolerance threshold, the test result is deemed unqualified; if any peak value reaches more than 90% of the tolerance threshold, an early warning message is output. S64. Output and store the test results, including real-time force curve, deformation curve, shear stress curve, peak data and judgment results.

10. The automatic testing method for surface forces on an LCD according to claim 1, characterized in that, It also includes system calibration steps before testing and repeatability verification steps after testing; The system calibration steps include: using standard weights to perform multi-point calibration of the force acquisition unit within its range, and using standard gauge blocks to perform accuracy calibration of the displacement acquisition unit; The repeatability verification step includes: repeating steps S3 to S6 according to a preset number of test cycles, calculating the relative standard deviation of the multiple test results, and determining that the test data is valid if the relative standard deviation is less than the preset deviation; otherwise, retesting.

Images