A wear resistance automated testing method and testing equipment for mobile phone protective films

Abstract

The present invention relates to the field of wear resistance testing, and specifically to an automated test method for the wear resistance of a mobile phone protective film and its testing equipment. The method first uses sandpaper of different mesh sizes to polish the mobile phone protective film while the grinding wheel rotates at different speeds. The mesh size of the target sandpaper, the rotation speed data of the target sandpaper when polishing the mobile phone protective film each time, the surface image of the mobile phone protective film after each polishing of the target sandpaper, and the surface distance between the mobile phone protective film and the grinding wheel after each polishing of the target sandpaper are combined to obtain the grinding effect value of the target sandpaper when polishing the mobile phone protective film each time. The sequence composed of the grinding effect values ​​of all sandpapers when polishing the mobile phone protective film all times is subjected to time series decomposition, and the wear resistance of the mobile phone protective film is evaluated based on the data changes of the trend items and the data distribution level of the residual items obtained by the decomposition. The present invention can more comprehensively and accurately evaluate the wear resistance of mobile phone protective films.

Description

Technical Field

[0001] The present invention relates to the field of wear resistance testing, and in particular to an automated testing method for the wear resistance of a mobile phone protective film and testing equipment thereof. Background Art

[0002] With the widespread use of smartphones and the continuous increase in screen size, mobile phone protective films have become an indispensable accessory. Their main function is to prevent the screen from being scratched, worn, and even broken during daily use. Wear resistance, as a core performance indicator to measure the service life and protective effect of protective films, is directly related to consumers' usage experience and product reputation. Therefore, accurately, efficiently, and objectively evaluating the wear resistance of protective films is extremely important for manufacturers' quality control, new product development, and consumer purchases.

[0003] In related technologies, sandpaper with a single roughness or a fixed rotation speed is often used to test the wear resistance of mobile phone protective films. However, in daily use, mobile phone protective films will encounter friction from objects with different roughness (such as sand and keys) and different friction speeds (such as sliding and wiping). As a result, existing methods are unable to comprehensively and accurately evaluate the wear resistance of mobile phone protective films. Summary of the Invention

[0004] In order to solve the technical problem that existing methods cannot comprehensively and accurately evaluate the wear resistance of mobile phone protective films, the purpose of the present invention is to provide an automated test method and testing equipment for the wear resistance of mobile phone protective films. The technical solutions adopted are as follows:

[0005] The present invention provides an automated test method for the wear resistance of a mobile phone protective film, the method comprising:

[0006] While the grinding wheel rotates at different speeds, sandpaper of different mesh sizes on its surface is used to grind the mobile phone protective film, and the surface image of the mobile phone protective film and the surface distance between the mobile phone protective film and the grinding wheel are obtained after each grinding with different sandpapers. At the same time, the speed data of the different sandpapers during each grinding of the mobile phone protective film are obtained;

[0007] Using any type of sandpaper with any mesh size as the target sandpaper, the grinding effect value of the target sandpaper during each polishing of the mobile phone protective film is obtained based on the mesh size of the target sandpaper, the rotation speed data of the target sandpaper during each polishing of the mobile phone protective film, the difference between the surface image of the mobile phone protective film after each polishing by the target sandpaper and the original image of the unpolished mobile phone protective film, and the surface distance between the mobile phone protective film and the grinding wheel after each polishing by the target sandpaper;

[0008] According to the sandpaper polishing order, the sequence of grinding effect values ​​of all sandpapers when polishing the mobile phone protective film all times is used as the grinding effect change sequence; the grinding effect change sequence is time-series decomposed to obtain the trend item sequence, residual item sequence and grinding effect cycle of the grinding effect change sequence; based on the grinding effect cycle, the trend item sequence is evenly segmented to obtain multiple data segments of the trend item sequence; based on the data change of each data segment of the trend item sequence and the overall distribution level of the residual item sequence data, the wear resistance of the mobile phone protective film is obtained;

[0009] Based on the wear resistance, the wear resistance of the mobile phone protective film is evaluated.

[0010] Furthermore, obtaining the grinding effect value of the target sandpaper each time it polishes the mobile phone protective film includes:

[0011] Performing negative correlation normalization processing on the mesh size of the target sandpaper to obtain the roughness of the target sandpaper, and integrating the roughness of the target sandpaper and the rotation speed data of the target sandpaper when polishing the mobile phone protective film each time to obtain the friction factor of the target sandpaper when polishing the mobile phone protective film each time;

[0012] The degree of damage to the mobile phone protective film caused by the target sandpaper during each polishing operation is obtained based on the gradient distribution difference and grayscale distribution difference between the surface image of the mobile phone protective film after each polishing operation and the original image of the mobile phone protective film without polishing.

[0013] Using the degree of damage of the target sandpaper each time it polishes the mobile phone protective film, the rotation speed data of the target sandpaper each time it polishes the mobile phone protective film, the surface distance between the mobile phone protective film and the polishing wheel after each polishing, and the roughness of the target sandpaper are integrated to obtain a polishing intensification coefficient of the target sandpaper each time it polishes the mobile phone protective film;

[0014] The grinding effect value of the target sandpaper each time the mobile phone protective film is polished is obtained by combining the grinding intensification coefficient and the friction factor.

[0015] Furthermore, obtaining the degree of damage of the target sandpaper each time the mobile phone protective film is polished includes:

[0016] The difference between the grayscale information entropy of the surface image of the mobile phone protective film after each polishing by the target sandpaper and the grayscale information entropy of the original image of the mobile phone protective film without polishing is used as the numerator, the grayscale information entropy of the original image of the mobile phone protective film without polishing is used as the denominator, and the ratio is used as the grayscale information deviation of the surface image of the mobile phone protective film after each polishing by the target sandpaper;

[0017] The difference between the gradient information entropy of the surface image of the mobile phone protective film after each polishing by the target sandpaper and the gradient information entropy of the original image of the mobile phone protective film without polishing is used as the numerator, the gradient information entropy of the original image of the mobile phone protective film without polishing is used as the denominator, and the ratio is used as the gradient information deviation of the surface image of the mobile phone protective film after each polishing by the target sandpaper;

[0018] The sum of the grayscale information deviation and the gradient information deviation is normalized to obtain the degree of damage of the target sandpaper each time the mobile phone protective film is polished.

[0019] Furthermore, the obtained grinding intensification coefficient of the target sandpaper each time the mobile phone protective film is polished includes:

[0020] Based on the degree of damage of the target sandpaper each time the mobile phone protective film is polished, a first material coefficient and a second material coefficient of the target sandpaper each time the mobile phone protective film is polished are obtained, wherein the sum of the degree of damage, the first material coefficient, and the second material coefficient is equal to 1, and when the mobile phone protective film is made of a brittle material, the first material coefficient is greater than the second material coefficient, and when the mobile phone protective film is made of a non-brittle material, the first material coefficient is less than the second material coefficient;

[0021] The degree of damage, the first material coefficient, and the second material coefficient are used to weightedly sum and normalize the surface distance between the mobile phone protective film and the grinding wheel after each grinding of the target sandpaper, the roughness of the target sandpaper, and the rotation speed data of the target sandpaper when grinding the mobile phone protective film each time, to obtain the grinding intensification coefficient of the target sandpaper when grinding the mobile phone protective film each time.

[0022] Furthermore, obtaining the trend term sequence, residual term sequence and grinding effect cycle of the grinding effect variation sequence includes:

[0023] The STL time series decomposition algorithm is used to decompose the grinding effect variation sequence into a periodic term sequence, a trend term sequence and a residual term sequence, and the period length of the periodic term sequence is used as the grinding effect period of the grinding effect variation sequence.

[0024] Furthermore, the lengths of the data segments of the trend item sequence are the same, and the length of each data segment is equal to the grinding effect period of the grinding effect variation sequence.

[0025] Furthermore, the wear resistance of the mobile phone protective film is obtained by:

[0026] Perform straight line fitting on all data in each data segment of the trend item sequence, and use the slope of the fitted straight line of each data segment as the trend coefficient of each data segment;

[0027] Perform curve fitting on all data in the trend item sequence, and take the average value of the second-order derivative of the fitted curve at all data positions as the change characteristic value of the trend item sequence;

[0028] Obtaining the wear growth degree of the mobile phone protective film according to the difference in the trend coefficients of two adjacent data segments of the trend item sequence and the change characteristic value of the trend item sequence;

[0029] After synthesizing the mean and standard deviation of all data in the residual term sequence and performing negative correlation mapping, a first wear resistance coefficient of the mobile phone protective film is obtained. A negative correlation mapping is performed on the wear growth of the mobile phone protective film to obtain a second wear resistance coefficient of the mobile phone protective film. A negative correlation mapping is performed on the number of sandpapers of different mesh sizes on the grinding wheel and the difference in the grinding effect cycle of the grinding effect variation sequence to obtain a third wear resistance coefficient of the mobile phone protective film.

[0030] The first wear resistance coefficient, the second wear resistance coefficient and the third wear resistance coefficient are integrated and normalized to obtain the wear resistance of the mobile phone protective film.

[0031] Furthermore, obtaining the wear growth of the mobile phone protective film includes:

[0032] Based on the calculation formula of the wear growth degree, the wear growth degree of the mobile phone protective film is obtained. The calculation formula of the wear growth degree is:

[0033]

[0034] in, Indicates the wear growth of the mobile phone protective film; The change characteristic value representing the trend item sequence; The first The trend coefficient of each data segment; The first The trend coefficient of each data segment; The first The serial number value corresponding to each data segment; The number of data segments representing the trend item sequence; Expressed as a natural constant An exponential function with base .

[0035] Furthermore, the evaluation of the wear resistance of the mobile phone protective film includes:

[0036] If the wear resistance of the mobile phone protective film is greater than the preset first wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as first-level wear resistance;

[0037] If the wear resistance of the mobile phone protective film is greater than the preset second wear resistance threshold and not greater than the preset first wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as level 2 wear resistance;

[0038] If the wear resistance of the mobile phone protective film is greater than the preset third wear resistance threshold and not greater than the preset second wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as level three wear resistance;

[0039] If the wear resistance of the mobile phone protective film is not greater than the preset third wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as level four wear resistance, wherein the wear resistance of level one wear resistance, level two wear resistance, level three wear resistance and level four wear resistance decreases step by step.

[0040] The present invention also proposes an automated testing device for the wear resistance of a mobile phone protective film, the testing device including a grinding wheel, sandpaper of different mesh sizes evenly attached to the surface of the grinding wheel, and the grinding wheel rotating at different speeds. The testing device also includes a wear resistance evaluation module for testing the wear resistance of the mobile phone protective film, a camera device for obtaining a surface image of the mobile phone protective film after each grinding with different sandpapers, a distance sensor for measuring the surface distance between the mobile phone protective film and the grinding wheel after each grinding with different sandpapers, and a speed sensor for obtaining speed data of the mobile phone protective film when different sandpapers are used to grind the mobile phone protective film each time. The wear resistance evaluation module samples and connects the camera device, the distance sensor, and the speed sensor, and processes the obtained surface image, surface distance, and speed data to implement any one of the steps of the automated testing method for the wear resistance of the mobile phone protective film.

[0041] The present invention has the following beneficial effects:

[0042] The present invention takes into account that the existing methods are unable to comprehensively and accurately evaluate the wear resistance of mobile phone protective films. Therefore, by combining sandpapers of various roughnesses on the grinding wheel and gradually increasing the rotation speed of the grinding wheel, the friction situation of the mobile phone protective film in daily use is truly simulated, providing a more reliable wear resistance test. During the grinding process, the mesh size of the sandpaper, the rotation speed data of the grinding wheel, the surface image of the mobile phone protective film, and the distance between the mobile phone protective film and the grinding wheel are analyzed. The obtained grinding effect value reflects the cumulative effect of grinding on the mobile phone protective film based on the change in the mesh size of the sandpaper and the change in the friction speed. The grinding effect change sequence is decomposed in time series, and the data change trends of the multiple data segments divided into the trend item sequence obtained by the decomposition, as well as the overall data distribution level of the residual item sequence, are analyzed. The wear resistance of the mobile phone protective film is reflected by the obtained wear resistance, thereby achieving a comprehensive evaluation of the wear resistance of the mobile phone protective film. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 A flow chart of an automated test method for the wear resistance of a mobile phone protective film provided by one embodiment of the present invention;

[0045] Figure 2 A schematic diagram of an automated test scenario for the wear resistance of a mobile phone protective film provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0046] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail the automated wear resistance testing method and testing equipment for mobile phone protective films, including their specific implementation, structure, features, and effectiveness. In the following description, references to different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0047] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0048] The following describes in detail a method for automatically testing the wear resistance of a mobile phone protective film and a specific solution of the testing equipment thereof provided by the present invention in conjunction with the accompanying drawings.

[0049] See also Figure 1 , which shows a flow chart of an automated test method for the wear resistance of a mobile phone protective film provided by one embodiment of the present invention, the method comprising:

[0050] Step S1: While the grinding wheel rotates at different speeds, the mobile phone protective film is polished using sandpaper of different mesh sizes on its surface, and the surface image of the mobile phone protective film after each polishing with different sandpapers and the surface distance between the mobile phone protective film and the grinding wheel are obtained. At the same time, the speed data of the different sandpapers when polishing the mobile phone protective film each time are obtained.

[0051] Since the front of the mobile phone protective film is the part that is subject to the highest frequency of friction in daily use, especially the center area, in order to test the wear resistance of the front part of the mobile phone protective film, it is necessary to contact the front of the mobile phone protective film with the grinding wheel, and maximize the contact area between the grinding wheel and the front of the mobile phone protective film to ensure the reliability of the wear resistance test results of the mobile phone protective film.

[0052] First, a mobile phone protective film is secured to a curved film carrier plate, thereby deforming and bending the mobile phone protective film through the curved film carrier plate. The maximum curvature of the bending does not exceed the bending limit of the mobile phone protective film. The diameter of the grinding wheel is set so that the maximum curvature of the grinding wheel does not exceed the curvature limit of the mobile phone protective film. Then, multiple sandpapers of different grits are attached around the grinding wheel, and the grinding wheel is made to fit the bent mobile phone protective film as closely as possible. The grinding wheel angle is divided into equal sections to form multiple equally divided angular regions. Sandpaper is attached to each equally divided angular region in an order of increasing or decreasing grit. In one embodiment of the present invention, the different grit types of sandpaper can be, for example, #100, #400, #700, #1000, and #1300. The grit of the sandpaper is inversely proportional to its surface roughness, i.e., a larger grit indicates a lower surface roughness. Sandpapers of different grits are used to simulate friction objects of varying roughness.

[0053] At the same time, in order to simulate different friction speeds, the embodiment of the present invention also needs to make the grinding wheel rotate at different speeds. In one embodiment of the present invention, the initial speed of the grinding wheel can be set to 1rps, and the speed is increased by 1rps every time the grinding wheel rotates one circle until the speed of the grinding wheel reaches 20rps, and then the grinding of the mobile phone protective film is stopped. Figure 2 , which shows a schematic diagram of an automated test scenario for the wear resistance of a mobile phone protective film provided by an embodiment of the present invention.

[0054] Then start the grinding wheel and grind the mobile phone protective film according to the above-set speed rules. When the grinding wheel rotates at different speeds, sandpaper of different mesh sizes on its surface will grind the mobile phone protective film, and the surface image of the mobile phone protective film after each grinding with different sandpapers is collected by the camera device, where the surface image is a grayscale image. The surface distance between the mobile phone protective film and the grinding wheel after each grinding with different sandpapers is collected by the distance sensor, and the speed data of the different sandpapers when grinding the mobile phone protective film each time is collected by the speed sensor.

[0055] It should be noted that the dimensions of the numerical data obtained above are different. Therefore, the embodiment of the present invention also needs to standardize the numerical data to eliminate the influence of the dimension. Data standardization is a technical means well known to those skilled in the art and will not be elaborated here.

[0056] Step S2: Using any type of sandpaper with any mesh size as the target sandpaper, obtaining the grinding effect value of the target sandpaper each time the mobile phone protective film is polished based on the mesh size of the target sandpaper, the rotation speed data of the target sandpaper each time the mobile phone protective film is polished, the difference between the surface image of the mobile phone protective film after each polishing by the target sandpaper and the original image of the unpolished mobile phone protective film, and the surface distance between the mobile phone protective film and the grinding wheel after each polishing by the target sandpaper.

[0057] In the process of polishing a mobile phone protective film using sandpaper of different roughness, as the rotation speed of the grinding wheel continues to increase and the wear caused by the friction of the sandpaper on the mobile phone protective film accumulates, the damage to the mobile phone protective film will become more and more serious. In order to effectively determine the wear suffered by the mobile phone protective film and facilitate the subsequent acquisition of the wear resistance analysis results of the mobile phone protective film, the embodiment of the present invention first uses any type of sandpaper with a mesh size as the target sandpaper, and combines the mesh size of the target sandpaper, the rotation speed data of the target sandpaper when polishing the mobile phone protective film each time, the difference between the surface image of the mobile phone protective film after each polishing by the target sandpaper and the original image of the unpolished mobile phone protective film, and the surface distance between the mobile phone protective film and the grinding wheel after each polishing by the target sandpaper to perform analysis. The obtained grinding effect value reflects the degree of aggravated friction caused by the target sandpaper on the mobile phone protective film each time it polishes the mobile phone protective film, reflecting the cumulative effect of grinding on the mobile phone protective film based on the changes in the mesh size and rotation speed of the sandpaper.

[0058] Preferably, in one embodiment of the present invention, the method for obtaining the grinding effect value of the target sandpaper each time it polishes the mobile phone protective film specifically includes:

[0059] First, when using sandpaper of different mesh sizes to rub the mobile phone protective film, the smaller the mesh size of the sandpaper, the higher its roughness, and the corresponding grinding effect will be higher. And when the friction speed (i.e. the rotation speed of the grinding wheel) is higher, the grinding effect on the mobile phone protective film will also be higher. Therefore, the mesh size of the target sandpaper can be negatively correlated and normalized to obtain the roughness of the target sandpaper. The roughness of the target sandpaper and the rotation speed data of the target sandpaper when polishing the mobile phone protective film each time are combined to obtain the friction factor of the target sandpaper when polishing the mobile phone protective film each time. The larger the friction factor, the stronger the friction effect generated by the target sandpaper each time the mobile phone protective film is polished.

[0060] In one embodiment of the present invention, a negative exponential function with the natural constant e as the base can be used to implement normalization of negative correlation, and the normalization of negative correlation in subsequent steps can all be processed using the negative exponential function with the natural constant e as the base.

[0061] In an embodiment of the present invention, the sum or product of the roughness of the target sandpaper and the rotation speed data of the target sandpaper each time when polishing the mobile phone protective film can be used as the friction factor of the target sandpaper each time when polishing the mobile phone protective film, so as to achieve a combination of the two. This is not limited here, and the subsequent steps of the comprehensive processing of two or more data can also be achieved using the same method.

[0062] As an example, in one embodiment of the present invention, the friction factor of the target sandpaper when polishing the mobile phone protective film each time can be specifically expressed as follows:

[0063]

[0064] in, Indicates that the target sandpaper is The friction factor when polishing the mobile phone protective film for the first time; Indicates the mesh size of the target sandpaper; Indicates the roughness of the target sandpaper; Indicates that the target sandpaper is The rotation speed data when polishing the mobile phone protective film for the first time; Expressed as a natural constant An exponential function with base , used for normalization of negative correlation.

[0065] Then, during the process of sandpaper polishing the mobile phone protective film, the wear of the surface of the mobile phone protective film is monitored by a camera device. During the friction process, the wear of the mobile phone protective film increases with continuous friction, causing the mobile phone protective film to gradually become blurred in the image. Therefore, the degree of damage of the target sandpaper each time it polishes the mobile phone protective film can be obtained based on the gradient distribution difference and grayscale distribution difference between the surface image of the mobile phone protective film after each polishing by the target sandpaper and the original image of the unpolished mobile phone protective film. The greater the degree of damage, the higher the degree of wear on the surface of the mobile phone protective film after each polishing by the target sandpaper.

[0066] Preferably, in one embodiment of the present invention, the method for obtaining the degree of damage of the target sandpaper each time the target sandpaper is used to polish the mobile phone protective film specifically includes:

[0067] The difference between the grayscale information entropy of the surface image of the mobile phone protective film after each polishing by the target sandpaper and the grayscale information entropy of the original image of the unpolished mobile phone protective film is used as the numerator, and the grayscale information entropy of the original image of the unpolished mobile phone protective film is used as the denominator. The ratio is used as the grayscale information deviation of the surface image of the mobile phone protective film after each polishing by the target sandpaper. The greater the grayscale information deviation, the greater the grayscale information difference between the surface image of the mobile phone protective film after each polishing by the target sandpaper and the original image, which further indicates that the degree of wear of the mobile phone protective film is greater.

[0068] The difference between the gradient information entropy of the surface image of the mobile phone protective film after each polishing by the target sandpaper and the gradient information entropy of the original image of the unpolished mobile phone protective film is used as the numerator, and the gradient information entropy of the original image of the unpolished mobile phone protective film is used as the denominator. The ratio is used as the gradient information deviation of the surface image of the mobile phone protective film after each polishing by the target sandpaper. The greater the gradient information deviation, the greater the gradient information difference between the surface image of the mobile phone protective film and the original image after each polishing by the target sandpaper, which further indicates that the degree of wear of the mobile phone protective film is greater.

[0069] It should be noted that the calculation methods of the grayscale information entropy and gradient information entropy of an image are well known to those skilled in the art and will not be elaborated here.

[0070] Normalize the sum of grayscale information deviation and gradient information deviation, and limit the calculation result to range, thereby obtaining the degree of damage to the target sandpaper each time it polishes the mobile phone protective film.

[0071] In one embodiment of the present invention, an activation function can be used to implement normalization processing, and the same method can also be used to implement normalization processing in subsequent steps. In other embodiments of the present invention, maximum and minimum value normalization processing can be selected according to a specific range of numerical values, which will not be further described or limited.

[0072] As an example, in one embodiment of the present invention, the expression for the degree of damage of the target sandpaper each time it polishes the mobile phone protective film can be specifically, for example, as follows:

[0073]

[0074] in, Indicates that the target sandpaper is The degree of damage to the mobile phone protective film during the first polishing; Indicates that the target sandpaper is Grayscale information entropy of the surface image of the mobile phone protective film after the first polishing; Represents the grayscale information entropy of the original image of the unpolished mobile phone protective film; Indicates that the target sandpaper is The grayscale information deviation of the surface image of the mobile phone protective film after the first polishing; Indicates that the target sandpaper is The gradient information entropy of the surface image of the mobile phone protective film after the first polishing; Represents the gradient information entropy of the original image of the unpolished mobile phone protective film; Indicates that the target sandpaper is The gradient information deviation of the surface image of the mobile phone protective film after the first polishing; Represents the activation function, which is used for normalization.

[0075] Furthermore, in the actual grinding process, sandpaper can easily damage the mobile phone protective film. After the damage to the mobile phone protective film, the roughness of the mobile phone protective film increases, thereby aggravating the degree of damage caused by the sandpaper to the mobile phone protective film. Therefore, the degree of damage of the target sandpaper each time the mobile phone protective film is polished can be used. The rotation speed data of the target sandpaper each time the mobile phone protective film is polished, the surface distance between the mobile phone protective film and the grinding wheel after each polishing of the target sandpaper, and the roughness of the target sandpaper are combined to obtain the grinding aggravation coefficient of the target sandpaper each time the mobile phone protective film is polished. The grinding aggravation coefficient is used to describe the degree to which the target sandpaper aggravates the damage to the mobile phone protective film. The larger the grinding aggravation coefficient, the greater the degree of further damage to the mobile phone protective film caused by the target sandpaper when rubbing the mobile phone protective film, under the influence of the previous friction process and the roughness and friction speed of the target sandpaper.

[0076] Preferably, in one embodiment of the present invention, the method for obtaining the grinding intensification coefficient of the target sandpaper each time the mobile phone protective film is polished specifically includes:

[0077] Based on the degree of damage of the target sandpaper when polishing the mobile phone protective film each time, the first material coefficient and the second material coefficient of the target sandpaper when polishing the mobile phone protective film each time are obtained, wherein the sum of the degree of damage, the first material coefficient and the second material coefficient is equal to the value 1, and the degree of damage, the first material coefficient and the second material coefficient are used to perform weighted summation and normalization on the surface distance between the mobile phone protective film and the polishing wheel after each polishing of the target sandpaper, the roughness of the target sandpaper and the speed data of the target sandpaper when polishing the mobile phone protective film each time, and the calculation result is limited to range, thereby obtaining the grinding intensification coefficient of the target sandpaper each time it grinds the mobile phone protective film.

[0078] At the same time, when brittle materials are locally damaged, more serious surface peeling will occur due to the friction caused by the high roughness of the sandpaper. It can be seen that when the mobile phone protective film is a brittle material (such as a tempered film), it is more sensitive to the roughness of the sandpaper. Therefore, when the mobile phone protective film is a brittle material, it is necessary to make the first material coefficient greater than the second material coefficient. For non-brittle materials, due to the elasticity of their surface, there will be a certain absorption process of the friction effect generated during the friction process. However, due to the further energy absorption generated during the friction process, damage will occur due to local heat accumulation during high-speed friction. It can be seen that when the mobile phone protective film is a non-brittle material (such as a hydrogel film), it is more sensitive to the friction speed of the sandpaper. Therefore, when the mobile phone protective film is a non-brittle material, it is necessary to make the first material coefficient smaller than the second material coefficient.

[0079] As an example, in one embodiment of the present invention, the expression of the grinding intensification coefficient of the target sandpaper each time it grinds the mobile phone protective film can be specifically, for example, as follows:

[0080]

[0081] in, Indicates that the target sandpaper is The grinding intensification coefficient when grinding the mobile phone protective film for the first time; Indicates that the target sandpaper is The degree of damage to the mobile phone protective film during the first polishing; Indicates that the target sandpaper is The surface distance between the phone protective film and the grinding wheel after the first grinding; Indicates the roughness of the target sandpaper; Indicates that the target sandpaper is The rotation speed data when polishing the mobile phone protective film for the first time; Represents the activation function, which is used for normalization processing; and Respectively represent the target sandpaper in When polishing the mobile phone protective film for the first time, the first material coefficient and the second material coefficient, in one embodiment of the present invention, when the mobile phone protective film is made of brittle material, can be made , When the mobile phone protective film is made of non-brittle material, , , which is not limited here.

[0082] Finally, the grinding effect value of the target sandpaper each time it polishes the mobile phone protective film is obtained by combining the grinding aggravation coefficient and the friction factor when the target sandpaper polishes the mobile phone protective film each time.

[0083] As an example, in one embodiment of the present invention, the expression of the grinding effect value of the target sandpaper each time it grinds the mobile phone protective film can be specifically, for example, as follows:

[0084]

[0085] in, Indicates that the target sandpaper is Grinding effect value when polishing the mobile phone protective film for the first time; Indicates that the target sandpaper is The grinding intensification coefficient when grinding the mobile phone protective film for the first time; Indicates that the target sandpaper is The friction factor when polishing the mobile phone protective film for the first time; Expressed as a natural constant An exponential function with base .

[0086] The same method as above can be used to obtain the grinding effect value of each type of sandpaper on the grinding wheel each time the mobile phone protective film is polished.

[0087] Step S3: According to the sandpaper polishing order, the sequence consisting of the grinding effect values ​​of all sandpapers when polishing the mobile phone protective film all times is used as the grinding effect change sequence; the grinding effect change sequence is time-series decomposed to obtain the trend item sequence, residual item sequence and grinding effect cycle of the grinding effect change sequence; based on the grinding effect cycle, the trend item sequence is evenly segmented to obtain multiple data segments of the trend item sequence; according to the data changes of each data segment of the trend item sequence and the overall distribution level of the data of the residual item sequence, the wear resistance of the mobile phone protective film is obtained.

[0088] During the grinding process of the mobile phone protective film, there is a cumulative process of grinding effect, that is, as the friction time increases, more and more scratches will gradually appear on the mobile phone protective film, and the depth of the scratches is inconsistent. Moreover, when the grinding wheel rubs the mobile phone protective film at different rotation speeds and with sandpaper of different roughness, different degrees of grinding effects will be produced respectively. The more the mobile phone protective film can resist long-term friction and the grinding effects of high rotation speed and high roughness, the more it can reflect the excellent wear resistance of the mobile phone protective film. Therefore, the embodiment of the present invention first uses the grinding order of the sandpaper to form a sequence of grinding effect values ​​of all sandpapers when grinding the mobile phone protective film all times as a grinding effect change sequence. For example, in one embodiment of the present invention, assuming that a total of 3 types of sandpaper of mesh size are adhered to the grinding wheel, the sequence of grinding effect values ​​of all sandpapers when grinding the mobile phone protective film all times is: ,in, Indicates that the first type of sandpaper is The grinding effect value when polishing the mobile phone protective film for the first time, Indicates that the second type of sandpaper is The grinding effect value when polishing the mobile phone protective film for the first time, Indicates that the third type of sandpaper is The grinding effect value when polishing the mobile phone protective film for the first time, and Respectively represent the first Circle, the grinding effect values ​​of three types of sandpaper when polishing mobile phone protective film.

[0089] The grinding effect change sequence is decomposed into time series to obtain the trend item sequence, residual item sequence and grinding effect cycle of the grinding effect change sequence. The grinding effect cycle can then be used to segment the trend item sequence, and the data changes in each segment of the trend item sequence and the overall distribution level of the residual item sequence data can be analyzed to accurately evaluate the wear resistance of the mobile phone protective film.

[0090] Preferably, in one embodiment of the present invention, the method for obtaining the trend term sequence, the residual term sequence and the grinding effect period of the grinding effect variation sequence specifically includes:

[0091] The STL timing decomposition algorithm is used to decompose the grinding effect change sequence into a periodic item sequence, a trend item sequence and a residual item sequence, and the period length of the periodic item sequence is used as the grinding effect period of the grinding effect change sequence. The STL timing decomposition algorithm is a technical means well known to those skilled in the art and will not be described in detail here. It should also be noted that the periodic item sequence decomposed by the STL timing decomposition algorithm has a certain periodicity, and the method for obtaining the period length of the periodic item sequence is also a technical means well known to those skilled in the art and will not be described in detail here.

[0092] The trend item sequence is evenly segmented using the grinding effect cycle to obtain multiple data segments of the trend item sequence, wherein the lengths of the data segments of the trend item sequence are the same, and the length of each data segment is equal to the grinding effect cycle of the grinding effect change sequence.

[0093] Then, we combine the data changes of each data segment of the trend item sequence and the overall distribution level of the data of the residual item sequence for analysis. The obtained wear resistance reflects the wear resistance of the mobile phone protective film. Subsequently, we can conduct a more comprehensive and accurate evaluation of the wear resistance of the mobile phone protective film based on the wear resistance.

[0094] Preferably, in one embodiment of the present invention, the method for obtaining the wear resistance of the mobile phone protective film specifically includes:

[0095] First, a straight line fitting is performed on all the data in each data segment of the trend item sequence, and the slope of the fitted straight line of each data segment is used as the trend coefficient of each data segment. In one embodiment of the present invention, the existing least squares method or other methods can be used to achieve straight line fitting, which is not limited or elaborated here.

[0096] Curve fitting is performed on all data in the trend item sequence, and the average value of the second-order derivative of the obtained fitting curve at all data positions is used as the change characteristic value of the trend item sequence. Similarly, in one embodiment of the present invention, the existing least squares method or other methods can be used to achieve curve fitting, which is not limited or elaborated here.

[0097] Then, based on the difference in trend coefficients between two adjacent data segments of the trend item sequence and the changing characteristic value of the trend item sequence, the wear growth degree of the mobile phone protective film is obtained. The greater the wear growth degree, the more rapidly the wear of the mobile phone protective film increases after being continuously rubbed by sandpaper. Subsequently, the wear resistance of the mobile phone protective film can be evaluated based on the wear growth degree.

[0098] Preferably, in one embodiment of the present invention, the method for obtaining the wear growth of the mobile phone protective film specifically includes:

[0099] Based on the calculation formula of wear growth, the wear growth of the mobile phone protective film is obtained. The calculation formula of wear growth is:

[0100]

[0101] in, Indicates the wear growth of the mobile phone protective film; Indicates the changing characteristic value of the trend item sequence; The first The trend coefficient of each data segment; The first The trend coefficient of each data segment; The first The serial number value corresponding to each data segment; The number of data segments representing the trend item sequence; Expressed as a natural constant An exponential function with base .

[0102] Among them, the wear growth degree is used to describe the changing trend of the wear amount of the mobile phone protective film. The larger the wear growth degree, the higher the degree of rapid increase in the wear amount of the mobile phone protective film after continuous friction with sandpaper. At the same time, due to the self-acceleration effect of the mobile phone protective film during the wear process (such as scratches causing stress concentration), the later wear will aggravate the wear amount of the mobile phone protective film, so the later data segments are given a higher weight. , to express the cumulative effect acceleration weight, and the changing characteristic value of the trend term sequence The larger it is, the greater the wear rate increases with time, which is consistent with the nonlinear wear characteristics of mobile phone protective films.

[0103] Then, the mean and standard deviation of all data of the residual term sequence are integrated and negatively correlated to obtain the first wear resistance coefficient of the mobile phone protective film. The wear growth of the mobile phone protective film is negatively correlated to obtain the second wear resistance coefficient of the mobile phone protective film. The number of sandpapers of different mesh types on the grinding wheel and the difference of the grinding effect cycle of the grinding effect change sequence are negatively correlated to obtain the third wear resistance coefficient of the mobile phone protective film. The first wear resistance coefficient, the second wear resistance coefficient and the third wear resistance coefficient are integrated and normalized, and the calculation results are limited to range, thereby obtaining the wear resistance of the mobile phone protective film.

[0104] As an example, in one embodiment of the present invention, the expression for the wear resistance of the mobile phone protective film can be specifically, for example, as follows:

[0105]

[0106] in, Indicates the wear resistance of the mobile phone protective film; Represents the average value of all data in the residual sequence; Represents the standard deviation of all data in the residual series; Indicates the first wear resistance coefficient of the mobile phone protective film; Indicates the wear growth of the mobile phone protective film; Indicates the second wear resistance coefficient of the mobile phone protective film; Indicates the number of different grit sandpaper types on the grinding wheel; Grinding effect cycle representing the sequence of changes in grinding effect; Indicates the third wear resistance coefficient of the mobile phone protective film; Expressed as a natural constant An exponential function with base , used for negative correlation mapping; Represents the activation function, which is used for normalization processing; and Respectively represent the preset first adjustment parameter and the preset second adjustment parameter, which are used to prevent the denominator from being 0. and The value range is In one embodiment of the present invention, and are all set to 0.01, and The specific value of can also be set by the implementer according to the specific implementation scenario and is not limited here.

[0107] Among them, the lower the overall level of all data in the residual term sequence and the more concentrated the data distribution, that is, The smaller it is, the more stable the wear amount and wear accumulation process of the mobile phone protective film are, the less likely the surface layer is to experience high-frequency and large-scale wear and tear, and the better the wear resistance of the mobile phone protective film is. The smaller it is, the less likely the mobile phone protective film is to produce a large cumulative effect during the friction process, which leads to increasing wear and tear. This means that the wear resistance of the mobile phone protective film is better. At the same time, since the grinding wheel is used to grind the mobile phone protective film by rotating, the number of sandpapers of different mesh sizes on the grinding wheel can be considered as one grinding cycle. Therefore, The smaller it is, the slower the wear effect on the mobile phone protective film accumulates when polishing it, and the stronger the wear resistance of the mobile phone protective film.

[0108] It should be noted that in other embodiments of the present invention, negative correlation mapping may be achieved through other basic mathematical operations, which will not be described in detail here.

[0109] Step S4: Based on the wear resistance, the wear resistance of the mobile phone protective film is evaluated.

[0110] The greater the wear resistance of the mobile phone protective film, the stronger the wear resistance of the mobile phone protective film. Therefore, based on the wear resistance, a more comprehensive and accurate evaluation of the wear resistance of the mobile phone protective film is carried out.

[0111] Preferably, in one embodiment of the present invention, the method for evaluating the wear resistance of a mobile phone protective film specifically includes:

[0112] If the wear resistance of the mobile phone protective film is greater than a preset first wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as first-level wear resistance.

[0113] If the wear resistance of the mobile phone protective film is greater than the preset second wear resistance threshold and not greater than the preset first wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as level 2 wear resistance.

[0114] If the wear resistance of the mobile phone protective film is greater than the preset third wear resistance threshold and not greater than the preset second wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as level three wear resistance.

[0115] If the wear resistance of the mobile phone protective film is not greater than the preset third wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as four levels of wear resistance, among which the wear resistance of level one, level two, level three and level four decreases step by step, that is, level one has the strongest wear resistance and level four has the weakest wear resistance.

[0116] The ranges of the preset first wear resistance threshold, the preset second wear resistance threshold and the preset third wear resistance threshold are all , and the preset first wear resistance threshold is greater than the preset second wear resistance threshold, which is greater than the preset third wear resistance threshold. In one embodiment of the present invention, the preset first wear resistance threshold is set to 0.8, the preset second wear resistance threshold is set to 0.6, and the preset third wear resistance threshold is set to 0.4. The preset first wear resistance threshold, the preset second wear resistance threshold and the preset third wear resistance threshold can also be set by the implementer according to the specific implementation scenario, and are not limited here.

[0117] One embodiment of the present invention provides an automated testing device for the wear resistance of a mobile phone protective film. The testing device includes a grinding wheel, on the surface of which sandpaper of different mesh sizes is evenly attached, and the grinding wheel rotates at different speeds. The testing device also includes a wear resistance evaluation module for testing the wear resistance of the mobile phone protective film, a camera device for obtaining a surface image of the mobile phone protective film after each grinding with different sandpapers, a distance sensor for measuring the surface distance between the mobile phone protective film and the grinding wheel after each grinding with different sandpapers, and a speed sensor for obtaining speed data when different sandpapers are used to grind the mobile phone protective film each time. The wear resistance evaluation module samples and connects the camera device, the distance sensor, and the speed sensor, and processes the obtained surface image, surface distance, and speed data according to the method described in steps S1 to S4.

[0118] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0119] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

Claims

1. An automated test method for the wear resistance of a mobile phone protective film, characterized in that: The method comprises: While the grinding wheel rotates at different speeds, sandpaper of different mesh sizes on its surface is used to grind the mobile phone protective film, and the surface image of the mobile phone protective film and the surface distance between the mobile phone protective film and the grinding wheel are obtained after each grinding with different sandpapers. At the same time, the speed data of the different sandpapers during each grinding of the mobile phone protective film are obtained; Using any type of sandpaper with any mesh size as the target sandpaper, the grinding effect value of the target sandpaper during each polishing of the mobile phone protective film is obtained based on the mesh size of the target sandpaper, the rotation speed data of the target sandpaper during each polishing of the mobile phone protective film, the difference between the surface image of the mobile phone protective film after each polishing by the target sandpaper and the original image of the unpolished mobile phone protective film, and the surface distance between the mobile phone protective film and the grinding wheel after each polishing by the target sandpaper; According to the sandpaper polishing order, the sequence of grinding effect values ​​of all sandpapers when polishing the mobile phone protective film all times is used as the grinding effect change sequence; the grinding effect change sequence is time-series decomposed to obtain the trend item sequence, residual item sequence and grinding effect cycle of the grinding effect change sequence; based on the grinding effect cycle, the trend item sequence is evenly segmented to obtain multiple data segments of the trend item sequence; based on the data change of each data segment of the trend item sequence and the overall distribution level of the residual item sequence data, the wear resistance of the mobile phone protective film is obtained; Based on the wear resistance, the wear resistance of the mobile phone protective film is evaluated; The grinding effect value of the target sandpaper obtained each time the mobile phone protective film is polished includes: Performing negative correlation normalization processing on the mesh size of the target sandpaper to obtain the roughness of the target sandpaper, and integrating the roughness of the target sandpaper and the rotation speed data of the target sandpaper when polishing the mobile phone protective film each time to obtain the friction factor of the target sandpaper when polishing the mobile phone protective film each time; The degree of damage to the mobile phone protective film caused by the target sandpaper during each polishing operation is obtained based on the gradient distribution difference and grayscale distribution difference between the surface image of the mobile phone protective film after each polishing operation and the original image of the mobile phone protective film without polishing. Using the degree of damage of the target sandpaper each time it polishes the mobile phone protective film, the rotation speed data of the target sandpaper each time it polishes the mobile phone protective film, the surface distance between the mobile phone protective film and the polishing wheel after each polishing, and the roughness of the target sandpaper are integrated to obtain a polishing intensification coefficient of the target sandpaper each time it polishes the mobile phone protective film; Combining the grinding intensification coefficient and the friction factor, obtaining a grinding effect value of the target sandpaper each time the mobile phone protective film is polished; The degree of damage of the target sandpaper each time the mobile phone protective film is polished includes: The difference between the grayscale information entropy of the surface image of the mobile phone protective film after each polishing by the target sandpaper and the grayscale information entropy of the original image of the mobile phone protective film without polishing is used as the numerator, the grayscale information entropy of the original image of the mobile phone protective film without polishing is used as the denominator, and the ratio is used as the grayscale information deviation of the surface image of the mobile phone protective film after each polishing by the target sandpaper; The difference between the gradient information entropy of the surface image of the mobile phone protective film after each polishing by the target sandpaper and the gradient information entropy of the original image of the mobile phone protective film without polishing is used as the numerator, the gradient information entropy of the original image of the mobile phone protective film without polishing is used as the denominator, and the ratio is used as the gradient information deviation of the surface image of the mobile phone protective film after each polishing by the target sandpaper; Normalizing the sum of the grayscale information deviation and the gradient information deviation to obtain the degree of damage of the target sandpaper each time the mobile phone protective film is polished; The grinding aggravation coefficient of the target sandpaper each time the mobile phone protective film is polished includes: Based on the degree of damage of the target sandpaper each time the mobile phone protective film is polished, a first material coefficient and a second material coefficient of the target sandpaper each time the mobile phone protective film is polished are obtained, wherein the sum of the degree of damage, the first material coefficient, and the second material coefficient is equal to 1, and when the mobile phone protective film is made of a brittle material, the first material coefficient is greater than the second material coefficient, and when the mobile phone protective film is made of a non-brittle material, the first material coefficient is less than the second material coefficient; Using the damage degree, the first material coefficient, and the second material coefficient, weightedly sum and normalize the surface distance between the mobile phone protective film and the grinding wheel after each grinding with the target sandpaper, the roughness of the target sandpaper, and the rotation speed data of the target sandpaper when grinding the mobile phone protective film each time to obtain a grinding intensification coefficient of the target sandpaper when grinding the mobile phone protective film each time; The wear resistance of the mobile phone protective film includes: Perform straight line fitting on all data in each data segment of the trend item sequence, and use the slope of the fitted straight line of each data segment as the trend coefficient of each data segment; Perform curve fitting on all data in the trend item sequence, and take the average value of the second-order derivative of the fitted curve at all data positions as the change characteristic value of the trend item sequence; Obtaining the wear growth degree of the mobile phone protective film according to the difference in the trend coefficients of two adjacent data segments of the trend item sequence and the change characteristic value of the trend item sequence; After synthesizing the mean and standard deviation of all data in the residual term sequence and performing negative correlation mapping, a first wear resistance coefficient of the mobile phone protective film is obtained. A negative correlation mapping is performed on the wear growth of the mobile phone protective film to obtain a second wear resistance coefficient of the mobile phone protective film. A negative correlation mapping is performed on the number of sandpapers of different mesh sizes on the grinding wheel and the difference in the grinding effect cycle of the grinding effect variation sequence to obtain a third wear resistance coefficient of the mobile phone protective film. The first wear resistance coefficient, the second wear resistance coefficient, and the third wear resistance coefficient are integrated and normalized to obtain the wear resistance of the mobile phone protective film; The method for obtaining the wear growth of the mobile phone protective film comprises: Based on the calculation formula of the wear growth degree, the wear growth degree of the mobile phone protective film is obtained. The calculation formula of the wear growth degree is: in, Indicates the wear growth of the mobile phone protective film; The change characteristic value representing the trend item sequence; The first The trend coefficient of each data segment; The first The trend coefficient of each data segment; The first The serial number value corresponding to each data segment; The number of data segments representing the trend item sequence; Expressed as a natural constant An exponential function with base ; The evaluation of the wear resistance of the mobile phone protective film includes: If the wear resistance of the mobile phone protective film is greater than the preset first wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as first-level wear resistance; If the wear resistance of the mobile phone protective film is greater than the preset second wear resistance threshold and not greater than the preset first wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as level 2 wear resistance; If the wear resistance of the mobile phone protective film is greater than the preset third wear resistance threshold and not greater than the preset second wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as level three wear resistance; If the wear resistance of the mobile phone protective film is not greater than the preset third wear resistance threshold, the wear resistance of the mobile phone protective film is evaluated as level four wear resistance, wherein the wear resistance of level one wear resistance, level two wear resistance, level three wear resistance and level four wear resistance decreases step by step.

2. The method for automatically testing the wear resistance of a mobile phone protective film according to claim 1, characterized in that: The step of obtaining the trend term sequence, residual term sequence and grinding effect cycle of the grinding effect variation sequence includes: The STL time series decomposition algorithm is used to decompose the grinding effect variation sequence into a periodic term sequence, a trend term sequence and a residual term sequence, and the period length of the periodic term sequence is used as the grinding effect period of the grinding effect variation sequence.

3. The method for automatically testing the wear resistance of a mobile phone protective film according to claim 1, characterized in that: The lengths of the data segments of the trend item sequence are the same, and the length of each data segment is equal to the grinding effect period of the grinding effect variation sequence.

4. An automated test device for the wear resistance of a mobile phone protective film, the test device comprising a grinding wheel, characterized in that: Sandpaper of different mesh sizes is evenly attached to the surface of the grinding wheel, and the grinding wheel rotates at different speeds. The testing equipment also includes a wear resistance evaluation module for testing the wear resistance of the mobile phone protective film, a camera device for obtaining a surface image of the mobile phone protective film after each grinding with different sandpapers, a distance sensor for measuring the surface distance between the mobile phone protective film and the grinding wheel after each grinding with different sandpapers, and a speed sensor for obtaining speed data of the mobile phone protective film when different sandpapers are used to grind each time. The wear resistance evaluation module samples and connects the camera device, the distance sensor, and the speed sensor, and processes the obtained surface image, surface distance, and speed data to implement the steps of the method according to any one of claims 1 to 3.

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