Screen protection film assembly and method of manufacturing the same

Abstract

The application provides a screen protection film and a processing method thereof. The processing method comprises the following steps: (1) shielding treatment is performed on a glass to shield a non-etching area on the back surface of the glass and expose an etching area on the back surface of the glass; (2) etching treatment is performed on the glass to etch a groove on the back surface corresponding to the etching area; (3) after the etching treatment, CNC polishing treatment is performed on the side wall of the groove and the edge of the front surface of the glass by using a CNC processing device to form an inner arc edge on the back surface and an outer arc edge on the edge of the front surface of the glass; and (4) after the CNC polishing treatment, strengthening treatment is performed on the glass. The screen protection film processed by the processing method has high consistency with the arc of a screen and reduces the feeling of scratching hands.

Description

Technical Field

[0001] This invention relates to the field of screen protector technology, and more particularly to a screen protector assembly for electronic devices and its preparation method. Background Technology

[0002] When using mobile phones and other electronic devices, users typically apply a protective film to the screen to protect it. Currently, the physical edges of the glass panels on most mainstream mobile phone screens are curved. Traditional 2D protective films have flat surfaces on both sides and a nearly uniform thickness, making them unsuitable for the curvature of the screen's edges. 2.5D protective films have curved edges on the front and flat surfaces on the back (the side that adheres to the flat surface). If the width of the protective film matches the width of the screen, the edges cannot conform to the curvature of the screen edges, resulting in a scratchy feel on the sides after application. If the width of the protective film is reduced to match the width of the flat portion of the screen, the curved edges of the screen cannot be covered and protected. Both the front and back of the 3D protective film have curved edges, and the overall thickness of the glass is almost uniform. The overall shape of the 3D protective film matches the curved edge shape of the screen. However, the consistency between the curved edge shape of the 3D protective film and the curved edge shape of the screen still has a significant impact on the feel of the side. The curved edge part of the protective film processed by the existing 3D protective film processing technology has poor consistency with the curved edge part of the screen that needs to be matched, and there is still a problem of a scratchy feel. Summary of the Invention

[0003] Therefore, in order to overcome at least some of the defects and deficiencies in the prior art, the present invention provides a screen protector and a method for preparing the same, which can improve the consistency between the curved edge of the screen protector and the curved edge of the screen, and reduce the scratchy feeling.

[0004] Specifically, one aspect of the present invention provides a method for processing a screen protector, including: (1) The glass is shielded to shield the non-etched area on the back of the glass and expose the area to be etched on the back of the glass; (2) The glass is etched to create a groove on the opposite side corresponding to the area to be etched; (3) After etching, the sidewalls of the groove and the front edge of the glass are CNC polished using a CNC processing equipment to form an inner arc edge on the reverse side and an outer arc edge on the front edge of the glass. (4) After the CNC polishing process, the glass is subjected to a strengthening process.

[0005] In some embodiments, the CNC polishing process includes performing a first polishing process on the sidewall of the groove to form the inner arc edge, and then performing a second polishing process on the front edge of the glass to form the outer arc edge.

[0006] In some embodiments, the glass in the first polishing process and the second polishing process is fixed on the placement platform and both face the placement platform with their front sides facing the platform.

[0007] In some embodiments, the CNC processing equipment includes a grinding fixture, the grinding fixture including a first grinding head area and a second grinding head area spaced apart along its length; the first grinding head area is located at the end of the grinding fixture, the second grinding head area is arranged circumferentially around the grinding fixture and has an outer arc grinding surface, the outer arc grinding surface being recessed into the circumferential side surface of the grinding fixture; the first grinding process grinds the sidewall of the groove through the first grinding head area; the second grinding process grinds the front edge of the glass through the outer arc grinding surface.

[0008] In some embodiments, the shielding process includes screen printing on the reverse side of the glass to form a screen printing layer, wherein the area of ​​the reverse side covered by the screen printing layer forms the non-etched area; and the area of ​​the reverse side exposed outside the screen printing layer forms the etched area.

[0009] In some embodiments, the shielding process is followed by an encapsulation process, which specifically includes stacking two screen-printed glass sheets together with their reverse sides facing outwards to form a glass stack, and sealing the sides of the glass stack; the etching process specifically includes placing the encapsulated glass into a chemical etching solution for etching.

[0010] In some embodiments, the glass in the screen printing process, the encapsulation process, and the etching process is a glass substrate. After the screen printing process, multiple areas to be etched, corresponding one-to-one with multiple screen protectors, are formed on the reverse side of the glass substrate. After the etching process, multiple grooves are formed on the reverse side of the glass substrate. After the etching process and before the CNC polishing process, the glass substrate is further cut into multiple small pieces of glass, each small piece of glass having a groove on its reverse side. The CNC polishing process specifically involves processing each small piece of glass to form the inner arc edge and the outer arc edge of each small piece of glass.

[0011] In some embodiments, the strengthening process includes applying a coating to the front side of the glass to form a coating layer, wherein the water droplet angle of the coating layer is greater than or equal to 115°.

[0012] In some embodiments, the strengthening process includes tempering the glass; the glass is float glass, the tin side of the float glass is the reverse side of the glass, and the air side of the float glass is the front side of the glass.

[0013] This invention also provides a screen protector obtained by any of the screen protector methods described above.

[0014] In some embodiments, the screen protector includes a curved edge region and a flat region, wherein the difference between the thickness of the flat region and the thinnest thickness of the curved edge region is less than or equal to 0.03 mm. The embodiments of the present invention have at least the following beneficial effects: By first etching grooves on the reverse side and then performing CNC polishing to form the curved edges on both sides, the etching and CNC polishing processes do not alter the molecular gap structure of the original glass. Furthermore, the CNC polishing process allows for more controllable precision of the curved edges on both sides of the glass, better matching the curved edge shape of the screen, further reducing the scratchy feel and achieving a smoother touch. Larger areas and thicker parts of the flat area on the reverse side of the glass are removed through etching, with only the sides being polished. Roughly machining the overall concave shape before fine polishing reduces polishing time and difficulty. Etching also reduces the risk of glass breakage during processing, ensuring higher yield and lower costs. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a partial flowchart illustrating a screen protector processing method provided in an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the grinding fixture.

[0018] Figure 3 This is a partial flowchart illustrating a screen protector processing method provided in an embodiment of the present invention.

[0019] Figure 4 A schematic diagram showing the back of a glass substrate after screen printing.

[0020] Figure 5 This is a schematic diagram of the glass dimension markings provided in an embodiment of the present invention.

[0021] Figure 6 This is a schematic diagram of the glass arc height and thickness in an experiment provided for an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0023] This invention provides a screen protector and a method for processing the screen protector. The screen protector is mainly suitable for electronic devices with curved screen edges. Figure 1 It shows a portion of the area near the edge of the corresponding glass, according to Figure 1 As shown, the back of the glass 112 faces upwards, and the front of the glass 111 faces downwards. (Refer to...) Figure 1 The processing method of this screen protector includes: (1) The glass is shielded to shield the non-etched area on the back of the glass and expose the area to be etched on the back of the glass; (2) The glass is etched to create a groove on the opposite side corresponding to the area to be etched; (3) After etching, the sidewalls of the groove and the front edge of the glass are CNC ground using a CNC processing equipment to form an inner arc edge on the reverse side and an outer arc edge on the front edge of the glass. (4) After the CNC polishing process, the glass is subjected to a strengthening process.

[0024] In step (1), the shielding treatment of the glass is mainly to prepare for the etching treatment in step (2). The areas on the glass that do not need to be etched are shielded, for example, by forming a mask layer in the non-etching areas. For example, a mask layer can be formed by coating the areas on the glass that do not need to be etched, so that the non-etching areas on the back of the glass are shielded by the mask layer, and the areas to be etched are exposed without being covered by the mask layer.

[0025] The process may include a cutting step before the shielding treatment.

[0026] Cutting refers to slicing a large sheet of glass into the dimensions required for etching. In this embodiment of the invention, before etching, the large sheet of glass is first cut into intermediate glass pieces to serve as the glass substrate for both shielding and etching. The dimensions of the intermediate glass pieces correspond to multiple screen protectors. For example, if the large sheet of glass is 1100mm*1300mm and the screen protector corresponds to a 6-inch screen, then the dimensions of the intermediate glass pieces could be 540mm*427mm. The thickness of the glass raw material ranges from 0.33mm to 0.7mm.

[0027] After the shielding treatment, a first cleaning is performed to ensure the glass surface remains clean for the next process. This can be done using a cleaning agent with a pH value greater than 11 to remove impurities and dust from the glass surface. For example, a cleaning agent from Guangdong Jinquanfeng Technology Co., Ltd., model 501, can be used, with a 1:1 volume ratio of cleaning agent to water.

[0028] Etching processes, for example, involve chemically etching glass using an acidic etching solution. The glass is placed in an etching bath, where it reacts with the acid, causing the area to be etched on the reverse side of the glass to be etched away by the etching solution to remove a certain thickness (this thickness is determined by the difference between the thickness of the raw glass material and the thickness of the final protective film on the glass surface), thus forming a groove on the reverse side of the glass. The etching solution may include, for example, the following components by volume percentage: 25%–30% water, 30%–40% hydrofluoric acid, 8%–12% hydrochloric acid, and 2%–7% sulfuric acid. The etching time is adjusted according to the desired etching thickness, typically approximately 2–4 hours.

[0029] After etching and before CNC polishing, a second cleaning is required to neutralize any remaining etching solution on the glass surface and remove impurities and dirt. The cleaning conditions for the second cleaning can be the same as those for the first cleaning.

[0030] As mentioned above, if the middle glass is etched, after the second cleaning and before the first CNC polishing, the middle glass (i.e., the glass substrate) needs to be cut into smaller pieces of glass. Specifically, CCD cutting is used, that is, a cutting machine with CCD (Charge-coupled device) positioning is used for positioning and cutting, so that the difference between the outer dimensions of the cut glass and the required dimensions is controlled within 0.05mm.

[0031] CNC (Computer Numerical Control) polishing uses computer-controlled precision machine tools to perform high-precision and high-efficiency polishing of glass materials according to design drawings. For example... Figure 1 As shown, after etching, the sidewalls of the groove 113 on the reverse side 112 of the glass have not yet formed a smooth transition arc edge, and the un-etched edge of the front side 111 of the glass is a right angle. After CNC polishing, an outer arc edge 115 is formed on the edge of the front side 111 of the glass, and an inner arc edge 114 is formed on the reverse side 112, thus obtaining 3D glass.

[0032] In one related approach, 3D glass with curved edges can be obtained through a hot bending process. However, the hot bending process softens the glass and bends it to form the curve using a hot bending mold. The shape of the curved edge formed by the hot bending process is affected by many factors such as temperature, pressure, and time during hot pressing, making it difficult to control the precision. Therefore, it is difficult to ensure a high degree of consistency between the curved edge of the 3D glass and the curved edge of the screen to be coated when using this method to prepare a 3D protective film. In another related approach to preparing 3D glass, a lathe is used to directly grind the entire back of the glass to create a concave surface with curved edges. This whole-surface grinding method requires high-quality grinding tools, and when the height of the curved edge is large, the thickness of the glass that needs to be ground off is also greater. The processing time is long, and the glass is prone to breakage during processing. Using this method to prepare a 3D protective film will affect the strength performance of the glass and lead to a significant increase in processing costs.

[0033] The screen protector processing method provided in the above embodiments of this application mainly adopts a scheme of first etching grooves on the reverse side and then CNC polishing to form the curved edges on both sides (i.e., "etching + CNC polishing"). Compared with hot bending, this embodiment does not change the molecular gap structure of the original glass because both etching and CNC polishing do not change it. Moreover, CNC polishing makes the precision of the curved edges on both sides of the glass more controllable, which can better match the curved edge shape of the screen, thereby further reducing the scratchy feeling and obtaining a smoother feel. Compared with the scheme of polishing the entire surface to form a concave surface, in this embodiment, since a large area and a large thickness of the flat area on the back of the glass are removed by etching, only the side part is polished. The overall concave shape is first roughly processed and then finely polished, which can reduce the polishing time and the polishing difficulty. Etching can also reduce the risk of glass breakage during processing, ensuring higher yield and lower cost.

[0034] In some embodiments, such as Figure 1 As shown, the CNC polishing process includes first polishing the sidewall of the groove 113 to form the inner arc edge 114, and then second polishing the edge of the front surface 111 of the glass to form the outer arc edge 115. In this embodiment, since the edge of the front surface 111 of the glass is not thinned during the first polishing process, the glass thickness in the area corresponding to the sidewall of the groove 113 is still close to the thickness of the raw material glass, which can ensure that the glass edge has high strength and is not easily broken during the first polishing process.

[0035] In some embodiments, the glass in the first and second polishing processes is fixed on the placement platform, with its front side facing the platform. That is, during the transition from the first to the second polishing process, there is no need to flip the glass, thus eliminating the need for repositioning after flipping. During CNC polishing, positioning only needs to be performed before the first polishing process, improving the precision of CNC polishing and resulting in a smaller difference between the polished glass and the design dimensions. This further ensures the consistency between the final screen protector and the screen shape, reducing the scratchy feel.

[0036] In some embodiments, refer to Figure 2 As shown, the CNC processing equipment includes a grinding fixture 20, which includes a first grinding head area 21 and a second grinding head area 22 spaced apart along its length. The first grinding head area 21 is located at the end of the grinding fixture 20, and the second grinding head area 22 is arranged circumferentially around the grinding fixture 20 and has an outer arc grinding surface 221, which is recessed into the circumferential side of the grinding fixture. The first grinding process grinds the sidewall of the groove 113 through the first grinding head area 21. The second grinding process grinds the edge of the front surface 111 of the glass through the outer arc grinding surface 221. Thus, in the second grinding process, the glass does not need to be flipped over and the cutting head does not need to be replaced, which can further improve the accuracy of CNC grinding and reduce the scratchy feeling. In some embodiments, the thickness of the protective film glass planar area ( Figure 6 (T1) and the thinnest thickness of the arc edge region ( Figure 6 The difference between T1 and T2 (i.e., T1-T2) is controlled to be 0.03mm or less, ensuring the strength of the finished screen protector while taking into account the feel, so that it is not easily damaged during transportation.

[0037] In the first and second grinding processes, the rotation speed of the grinding fixture 20 is, for example, 36000±20% rpm, and the feed rate is 2000±20% mm per minute. This ensures grinding efficiency while avoiding insufficient precision due to excessive grinding speed.

[0038] In some embodiments, the shielding process employs screen printing, specifically using masking ink to screen print on the glass surface, ensuring that the printed areas are not etched in subsequent etching processes. The material of the masking ink is set according to the etching conditions in the etching process. For example, if the etching process uses an acidic etching solution, the masking ink should be an acid-resistant ink to resist the corrosion of the chemical solution. Specifically, screen printing is performed on the reverse side of the glass to form a screen-printed layer. The area on the reverse side of the glass covered by the masking ink (i.e., the area covered by the screen-printed layer) forms the non-etched area, while the area on the reverse side of the glass exposed outside the masking ink (screen-printed layer) forms the area to be etched. Compared to the process of forming a mask layer through coating, the screen-printed layer has a stronger bond strength with the glass surface, is less prone to coating blistering, and better ensures that the non-etched areas are not eroded by the etching solution, thus ensuring accuracy and a smooth feel.

[0039] In some embodiments, after the screen printing process (specifically after the first cleaning process), an encapsulation process is performed. This encapsulation process specifically includes stacking two screen-printed glass sheets together with their reverse sides 112 facing outwards to form a glass laminate (see reference). Figure 3 The sides of the glass stack are sealed to prevent the etching solution from flowing to the front side 111 of the glass through the side gaps during the etching process. The etching process specifically includes placing the encapsulated glass into a chemical etching solution for etching. A sealing tape resistant to etching solution corrosion can be used to encapsulate the sides of the glass stack. In the glass stack, the front sides of two pieces of glass are bonded together. After the sides are encapsulated, only the back side is exposed to contact with the etching solution. The area to be etched is not covered by screen printing and is etched into grooves by the etching solution. Since the front side of each piece of glass is shielded by the other piece, screen printing is not required to achieve a shielding effect on the front side of the glass, thus reducing the use of screen printing ink and lowering costs.

[0040] In some embodiments, the glass used in the screen printing process, the encapsulation process, and the etching process is a glass substrate, such as... Figure 4As shown, after the screen printing process, multiple etching areas corresponding to multiple screen protectors are formed on the reverse side of the glass substrate. After the etching process, multiple grooves will be formed on the reverse side of the glass substrate. The process includes cutting the glass substrate into multiple small glass pieces after the etching process and before the CNC polishing process, with each small glass piece having one groove on its reverse side. The CNC polishing process specifically involves processing each small glass piece separately to form the inner and outer curved edges of each piece. Screen printing on a large glass substrate improves efficiency and reduces errors compared to screen printing on small glass pieces individually. Encapsulating the laminated glass formed on the glass substrate allows only the four sides of the glass substrate to be encapsulated for multiple screen protectors, providing a wider side encapsulation area. This also reduces the number of encapsulation steps and the difficulty of encapsulation, and the front of the glass in the middle area is less susceptible to etching by the etching solution, improving the yield of the etching process.

[0041] For example, strengthening treatments can include polishing, tempering, acid bath treatment, and coating treatment.

[0042] Polishing is used to remove mold marks, scratches, and surface dust caused by CNC machining on glass surfaces. Polishing includes polishing both the front and back of the glass separately. Specifically, it includes polishing the front of the glass using a polishing mat and polishing the back using a polishing brush. The polishing mat is made of materials such as pure wool, synthetic fibers, or blended fibers, and can include straight and curly pile. The mat has a pile length of 5mm to 30mm, a single pile diameter of less than 0.1mm, and a density of 1300 hairs / cm² or higher. The polishing brush can be made of materials such as nylon bristles, boar bristles, or a mixture of bristles. The brush has a pile length of, for example, 20mm to 50mm, a single pile diameter of 0.2mm to 0.5mm, and a density of 100 to 150 hairs / cm². Since the front side is convex, a polishing mat can be used to polish the entire front of the glass. The back side is concave, and a polishing brush can be used to polish it, allowing the brush bristles to reach into the concave surface. This avoids the problem of not being able to polish the entire surface or applying too much pressure that could affect the curvature of the glass when using a polishing mat.

[0043] Polishing can be performed using HL-1615A abrasive from Zhongcheng Hailiang Company. The specific gravity of the polishing slurry is 1.06~1.12, which means the density of the polishing slurry is 1.06~1.12 g / cm³. 3 For example, the specific gravity of the polishing slurry can be 1.06, 1.08, 1.1, 1.12, etc. The polishing pressure is 4 kg / cm². 2 ~6kg / cm 2 For example, it could be 4kg / cm 25kg / cm 2 Or 6kg / cm 2 The front side uses a rotation speed of 10-15 RPM (RPM is an abbreviation for Revolutions Per Minute), and the reverse side uses a rotation speed of 260 RPM, with a polishing time of 16 minutes (8 minutes forward and 8 minutes reverse). By adjusting the specific gravity and pressure of the polishing slurry, it is possible to more efficiently remove mold marks, scratches, surface dust spots, etc. generated after hot bending, thereby improving the yield.

[0044] After polishing, for example, a third cleaning is performed before tempering. The parameters for the third cleaning can be the same as those for the first cleaning.

[0045] Tempering is used to harden the surface of glass. For example, the glass is first preheated in a furnace at 320-380℃ for 1 hour. After preheating, the glass is placed in a tempering salt solution at 360℃-440℃ for ion exchange for 1-3 hours. The tempering salt used is potassium nitrate with a concentration greater than 90%. If the glass is float glass, the tin side of the float glass is considered the reverse side, and the air side is considered the front side. The principle is that the tin side of the float glass has a tin layer. During the ion exchange process of tempering, potassium ions can penetrate to a shallower depth on the tin side compared to the air side. This causes the tin side and the air side to be subjected to inconsistent surface tension and internal stress during tempering, resulting in glass warping. Therefore, by using the tin side of the float glass as the reverse side, a large area of ​​the tin layer on the reverse side is removed during etching, making it less susceptible to the influence of the tin side on the glass warping during tempering. This further ensures the consistency of the tempered glass shape with the target shape.

[0046] After tempering, such as after the fourth cleaning, acid bath treatment is performed. Acid bath treatment is used to remove micro-cracks on the glass surface, small chipping defects on the sides, etc. For example, the chemical solution used in acid bath treatment is as follows by mass percentage: water 45%~50%, hydrofluoric acid 25%~30%, hydrochloric acid 8%~12%, sulfuric acid 2%~7%, and the acid bath time is 20~60 seconds.

[0047] After acid bath treatment, for example, after the fifth cleaning, a black border surrounding the viewing area is printed on the glass surface, corresponding to the screen window. The parameters for the fifth cleaning treatment can be the same as those for the first cleaning treatment. Specifically, printing ink can be used to print the black border surrounding the viewing area on the edge of the glass through a printing screen, and then the ink is cured by baking.

[0048] After printing the black border around the viewing window area, the glass surface is cleaned, and then a coating treatment is applied to the front of the glass to form a coating layer. The water droplet angle of the coating layer is greater than or equal to 115° to achieve a smoother feel. The water droplet angle is defined as the angle between the gas-liquid phase interface and the solid-liquid phase interface at the solid-liquid-gas three-phase interface, and can be used to evaluate the hydrophobic properties of the material. The coating layer can be, for example, an AF (Anti-Fingerprint) film or an AR (Anti-reflection) film. The coating process can specifically use vapor deposition or magnetron sputtering coating processes, using AF pellets or AR pellets as the target material for coating.

[0049] Before coating, the glass surface can be treated with plasma corona to further clean the dirt on the glass surface, so that the coating layer can adhere better to the glass during the coating process.

[0050] Finally, after the reinforcement process, there is also an assembly step, which may include applying AB glue, applying release film, assembling pull strap, assembling applicator, etc. AB glue is used to stick the protective film to the screen of the electronic device, the release film is used to protect the AB glue before sticking the protective film, the pull strap is connected to the release film and is used to remove the release film, and the applicator is used to assist in sticking the protective film to the screen of the electronic device.

[0051] In a series of experiments, 15 protective film glass sheets were obtained by processing the raw material glass using both Process 1 and Process 2. In Process 1, the CNC polishing process was performed using a polishing fixture 20 with a first polishing head area 21 and a second polishing head area 22, as provided in this embodiment. The glass did not need to be flipped. In Process 2, the CNC polishing process used two independent polishing heads. One polishing head performed the first polishing process, and the other polishing head performed the second polishing process. The glass needed to be flipped. After the first polishing process, the inner arc polishing head was replaced with an outer arc polishing head before the second polishing process. The remaining steps and parameters were the same. The specific process steps included cutting the raw material glass into middle sheets, screen printing on the reverse side of the middle sheets, cleaning, encapsulating the two middle sheets with the reverse side facing out, etching, cleaning, cutting the CCD into small glass sheets, first polishing, and second polishing. In both Process 1 and Process 2, Corning 1805 glass was used as the raw material. The glass thickness before etching was 0.70 mm, and the thickness of the planar area after etching ranged from 0.42 to 0.47 mm. Table 1 shows the results for Process 1, and Table 2 shows the results for Process 2. All dimensions are in millimeters. The corresponding positions for dimensions 1 to 5 are shown in the table. Figure 5 The measurement diagram of arc height is shown below. Figure 6The arc heights on both sides of the three cross-sections corresponding to the glass width direction were measured to obtain arc heights from 1 to 6. Cpk is the process capability index, a statistical indicator used to measure the "inherent capability" or "potential" of a stable process (production process) in meeting preset product specifications. Simply put, a higher Cpk indicates better stability.

[0052] Table 1

[0053] Table 2

[0054] The Cpk values ​​for each dimension in Table 1 are greater than those in Table 2, confirming that the CNC polishing process of Process 1 is more stable than that of Process 2, and the resulting glass curvature is more consistent with the target curvature.

[0055] In another set of experiments, protective film glass was prepared using the same process as process 1 above, and a screen protector with curved edges corresponding to the iPhone 17 Pro Max was finally prepared as the first set of samples. The same process as process 2 above was used to prepare the protective film glass, and a screen protector with curved edges corresponding to the iPhone 17 Pro Max was finally prepared as the second set of samples. Except for CNC polishing, the preparation conditions for the first and second sets of samples were identical. Finished product packaging tests were conducted on both sets of samples, including drop tests and roller tests. The drop test involved dropping the packaging box with one corner, three edges, and six surfaces facing down from a height of 1 meter, with each part dropped once. The roller test involved placing the finished packaging in a test roller 50 times, dropping it 10 times per minute (360° rotation of the roller counts as one drop) for two rounds. In the first set of samples, some screen protectors broke, while others remained intact. All samples in the second set remained unbroken. The thickness of the broken samples in the first group of samples was measured, and the thickness of a portion of the samples in the second group of samples was measured. The thickness T1 of the planar region and the thinnest thickness T2 of the arc edge of the broken samples in the first group of samples and the sampled samples in the second group of samples, as well as the difference between the two, are shown in Table 3 (unit: mm).

[0056]

[0057] According to Table 3, the difference between T1 and T2 in the broken samples of the first group is greater than 0.04 mm, while the difference between T1 and T2 in the sampled samples of the second group is less than 0.03 mm, and can even reach 0 mm. This indicates that a large difference between T1 and T2 thickness increases the risk of glass breakage during finished product transportation. The principle is as follows: If a piece of glass has a large thickness difference, a strength difference will occur at the high and low thickness locations, which can be analyzed using the central tensile stress formula CT=(CS×DOL) / (T-2×DOL). Where CT is the central tensile stress, CS is the surface compressive stress, and DOL is the depth of the compressive stress layer.

[0058] For example: a piece of glass with a flat area thickness of 0.25mm and a curved edge area thickness of 0.2mm, after tempering at 390℃ / 1h, has CS=800Mpa and DOL=15um; Therefore, the central tensile stress CT of the planar region is approximately 54 MPa (800 * 15) / (250 - 2 * 15) ≈ 54 MPa, and the central tensile stress CT of the arc-shaped region is approximately 70 MPa (800 * 15) / (200 - 2 * 15) ≈ 70 MPa. The greater the central tensile stress, the greater the risk of microcracks forming during object collisions. These microcracks gradually enlarge, eventually leading to breakage. On one hand, a larger CT (coulombic stress) in the curved edge region increases the risk of breakage. On the other hand, the significant difference in CT between the curved edge region and the planar region will cause abrupt stress changes in the thickness transition area, potentially generating additional shear stress or stress concentration, making this region more vulnerable.

[0059] Based on the analysis of the above experiments, CNC grinding without flipping or changing the cutting head can be performed by using a grinding fixture 20 to improve grinding accuracy and control the thickness difference between the flat area and the curved edge area of ​​the glass to less than 0.03mm, thus taking into account both the feel and the strength of the glass.

[0060] Furthermore, it is understood that the foregoing embodiments are merely illustrative examples of the present invention. Provided that the technical features do not conflict, the structure is not contradictory, and the purpose of the invention is not violated, the technical solutions of the various embodiments can be arbitrarily combined and used.

[0061] 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. A method for processing a screen protector, characterized in that, include: (1) The glass is shielded to shield the non-etched area on the back of the glass and expose the area to be etched on the back of the glass; (2) The glass is etched to create a groove on the opposite side corresponding to the area to be etched; (3) After etching, the sidewalls of the groove and the front edge of the glass are CNC polished using a CNC processing equipment to form an inner arc edge on the reverse side and an outer arc edge on the front edge of the glass. (4) After the CNC polishing process, the glass is subjected to a strengthening process.

2. The method for processing a screen protector as described in claim 1, characterized in that, The CNC polishing process includes a first polishing process on the sidewall of the groove to form the inner arc edge, and then a second polishing process on the front edge of the glass to form the outer arc edge.

3. The method for processing a screen protector as described in claim 2, characterized in that, In both the first and second polishing processes, the glass is fixed on the placement platform with its front facing the platform.

4. The method for processing a screen protector as described in claim 3, characterized in that, The CNC processing equipment includes a grinding fixture, which includes a first grinding head area and a second grinding head area spaced apart along its length. The first grinding head area is located at the end of the grinding fixture, and the second grinding head area is arranged circumferentially around the grinding fixture and has an outer arc grinding surface, which is recessed into the circumferential side of the grinding fixture. The first grinding process grinds the sidewall of the groove through the first grinding head area, and the second grinding process grinds the front edge of the glass through the outer arc grinding surface.

5. The method for processing a screen protector as described in claim 1, characterized in that, The shielding process includes screen printing on the reverse side of the glass to form a screen printing layer, the area of ​​the reverse side covered by the screen printing layer forming the non-etched area; and the area of ​​the reverse side exposed outside the screen printing layer forming the etched area.

6. The method for processing a screen protector as described in claim 5, characterized in that, The shielding process is followed by an encapsulation process, which specifically includes stacking two screen-printed glass sheets together with their reverse sides facing out to form a glass stack and sealing the sides of the glass stack; the etching process specifically includes placing the encapsulated glass into a chemical etching solution for etching.

7. The method for processing a screen protector as described in claim 6, characterized in that, In the silkscreen printing, encapsulation, and etching processes, the glass is a glass substrate. After the silkscreen printing, multiple etching areas corresponding to multiple screen protectors are formed on the reverse side of the glass substrate. After the etching, multiple grooves are formed on the reverse side of the glass substrate. After the etching and before the CNC polishing, the glass substrate is cut into multiple small pieces of glass, each small piece of glass having a groove on its reverse side. The CNC polishing specifically involves processing each small piece of glass to form an inner arc edge and an outer arc edge.

8. The method for processing a screen protector as described in claim 1, characterized in that, The strengthening process includes applying a coating to the front surface of the glass to form a coating layer, wherein the water droplet angle of the coating layer is greater than or equal to 115°.

9. A method for processing a screen protector as described in any one of claims 1 to 8, characterized in that, The strengthening process includes tempering the glass; the glass is float glass, the tin side of the float glass is the back side of the glass, and the air side of the float glass is the front side of the glass.

10. A screen protector, characterized in that, Obtained by the screen protector method as described in any one of claims 1 to 9.

11. The screen protector as described in claim 10, characterized in that, The screen protector includes an arc-shaped area and a flat area, wherein the difference between the thickness of the flat area and the thinnest thickness of the arc-shaped area is less than or equal to 0.03 mm.

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