Moire sheet

Abstract

The utility model provides a moire sheet, which comprises a moire sheet film and optical glass, and the edge of the moire sheet film is adhered to the optical glass.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of testing, and relates to a cloud pattern sheet. BACKGROUND

[0002] As an effective measurement auxiliary tool, the cloud pattern sheet on the market is made by forming a grating structure on optical glass through etching technology. The cloud pattern sheet made by this process has significantly increased difficulty as the size of the optical glass increases. Moreover, the large-size cloud pattern sheet is limited by materials and cannot guarantee the uniformity and accuracy of the grating. For example, it is difficult to achieve the precision required for measuring the surface warping degree of a lithium battery by increasing the size of the cloud pattern sheet to adapt to the size of the lithium battery. Therefore, to ensure measurement accuracy, the existing cloud pattern sheet is generally a small-size product, and such a cloud pattern sheet can only be applied to electronic components. SUMMARY

[0003] The utility model provides a cloud pattern sheet, which can effectively solve the above problems.

[0004] The utility model is implemented as follows:

[0005] The utility model provides a cloud pattern sheet for measuring the warping degree of a lithium battery, which comprises a cloud pattern sheet film and optical glass, and the edge of the cloud pattern sheet film is attached to the optical glass.

[0006] The utility model has the advantages of:

[0007] The utility model provides a cloud pattern sheet, which comprises a cloud pattern sheet film and optical glass, and the edge of the cloud pattern sheet film is attached to the optical glass.

[0008] Further, the cloud pattern sheet film is made of a material with a low coefficient of thermal expansion, which can prevent the optical performance or physical structure of the cloud pattern sheet from changing due to the high temperature of the battery surface during the test, thereby ensuring the accuracy of the measurement results.

[0009] Further, the cloud pattern sheet film adopts a concentric circle grating structure, which has high regularity and repeatability and is sensitive to slight deformation. The cloud pattern sheet can clearly and sensitively reflect the warping degree, and the warping degree can be quantified by observing the change in the cloud pattern. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained without creative labor on the basis of these drawings.

[0011] Figure 1 is a structural schematic view of the cloud pattern sheet provided by the embodiments of the present application.

[0012] Figure 2 is a schematic view of the warping deformation of the surface of a lithium battery.

[0013] Figure 3 is a structural schematic view of a test system for measuring the warping degree of the surface of a lithium battery using the cloud pattern sheet provided by the embodiments of the present application.

[0014] Figure 4 is a result view of the test system measuring the height of a spherical cap provided by the embodiments of the present application.

[0015] Figure 5 is a schematic view of the cloud pattern sheet placed on the surface of a lithium battery.

[0016] Figure 6 is a measurement result view of the warping degree of the surface of a 280 Ah lithium battery provided by the embodiments of the present application. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only to represent selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0018] The embodiments of the present application provide a cloud pattern sheet 1, please refer to Figure 1 The cloud pattern sheet 1 includes a cloud pattern sheet film 11 and optical glass 12, the edge of the cloud pattern sheet film 11 is pasted on the optical glass 12.

[0019] The cloud pattern sheet 1 is used for measuring the surface warping degree of a lithium battery.

[0020] Please refer to Figure 2 As shown in the figure, surface warping deformation during the production process is a common quality problem of lithium battery products. Surface warping may damage the structural stability of the battery, cause poor charge conduction in the battery, reduce the charge-discharge efficiency and cycle life of the battery, and may also damage the isolation film between the electrode and the electrolyte, increase the risk of short circuit of the battery, and even cause fire or explosion accidents.

[0021] In the embodiment of the utility model, the cloud pattern sheet film 11 etched with grating structure is pasted on the optical glass 12 to form the cloud pattern sheet 1. The etching process of the cloud pattern sheet film 11 is simpler than the optical glass 12, and the size problem can be overcome. The size precision and pitch precision of the grating formed thereon can meet the high-precision measurement requirements of the surface warping degree of the lithium battery.

[0022] Further, the cloud pattern sheet film 11 has poor toughness and will be bent when directly placed on the surface of the lithium battery, so it is pasted on the optical glass 12.

[0023] In particular, the cloud pattern sheet 1 can be used for measuring the surface warping degree of a large-size 280 Ah square battery.

[0024] In some embodiments, the material of the cloud pattern sheet film 11 is PET or PC.

[0025] When the cloud pattern sheet 1 is placed on the surface of the lithium battery, the direct contact surface is the corresponding surface of the cloud pattern sheet film 11. PET and PC both have good chemical stability, which can reduce the possible corrosion of the electrolyte on the cloud pattern sheet 1.

[0026] Moreover, PET and PC have a low coefficient of thermal expansion, which can reduce the thermal expansion and contraction of the material caused by changes in environmental temperature, preventing the cloud pattern and pitch precision from being affected.

[0027] In addition, PET and PC have good light transmittance.

[0028] In some embodiments, the coefficient of thermal expansion α 100 / 300℃ of the optical glass 12 is 1×10 -5 / K-1×10 -6 / K.

[0029] The coefficient of thermal expansion of the optical glass 12 is lower than that of the cloud pattern sheet film 11, so the optical glass 12 with a matching (10 -5 grade) coefficient of thermal expansion as the cloud pattern sheet film 11 should be selected as much as possible.

[0030] In some embodiments, the optical glass 12 has a length of 15-35 cm, a width of 15-35 cm, and a thickness of 1.5-2.5 mm.

[0031] 280 The size of the surface of the lithium battery is generally 15-25 cm.

[0032] The optical glass 12 needs to have a certain thickness to provide strength for the cloud film 11 connected thereto, so that the cloud film 11 is kept flat on the surface of the lithium battery to ensure the optical performance of the cloud film 11, so that the cloud pattern formed can clearly and sensitively reflect the degree of warping.

[0033] However, if the optical glass 12 is too thick, on the one hand, it will consume costs, including material costs and processing costs for manufacturing the cloud film 1. On the other hand, it is inevitable to increase the propagation distance of light in the glass 12, resulting in more light being absorbed and scattered, thereby reducing the light transmittance and the clarity of the cloud pattern obtained by the camera. In addition, the thickness of the glass will increase its coefficient of thermal expansion, thereby affecting the accuracy and stability of the optical system.

[0034] In some embodiments, the grating pitch on the cloud film 11 is 120-180 μm.

[0035] For the same degree of warping, as the grating pitch increases, the number of light and dark stripes in the cloud pattern formed during testing decreases, or in other words, the pitch of the stripes increases. If the grating pitch is too large, it will result in a lack of regularity in the light and dark stripes in the cloud pattern formed during testing, making it difficult to quantify the degree of warping by observing the changes in the cloud pattern.

[0036] If the grating pitch is too small, on the one hand, it will increase the manufacturing cost of the cloud film 11, and on the other hand, it will result in a too small pitch of the stripes in the cloud pattern formed, thereby making it difficult to distinguish the stripes.

[0037] In some embodiments, the gratings on the cloud film 1 are arranged in concentric circles.

[0038] Specifically, the center of the concentric circles is arranged at the center of the cloud film 1.

[0039] The cloud film 11 adopts a concentric circular grating structure, which has high regularity and repeatability, and is sensitive to small deformations, and can clearly and sensitively reflect the degree of warping, facilitating the quantification of the degree of warping by observing the changes in the cloud pattern.

[0040] The selection of the optical glass 12 and the cloud film 11 is mainly based on the following standards:

[0041] 1. High transparency:

[0042] It allows light to pass through efficiently, minimizing light absorption and scattering to ensure clear and realistic images. This is crucial for optical systems, enabling observers to obtain accurate and clear images.

[0043] 2. High chemical stability:

[0044] It does not readily react with other chemicals and has strong corrosion resistance. During long-term use, it maintains the stability of its optical properties and physical structure, and will not deteriorate or be damaged by contact with air, moisture, or chemical reagents.

[0045] In particular, compatibility with the lithium battery testing environment must be considered. Lithium batteries may contain chemicals such as electrolytes.

[0046] 3. Good uniformity of physical properties:

[0047] Its internal structure and physical properties are very uniform in all directions, which means that when light passes through the optical glass, its optical parameters such as refractive index and scattering rate are consistent regardless of which direction the light enters, thus ensuring the accuracy of the optical system and the quality of the images acquired by the camera.

[0048] 4. Specific and accurate optical constants:

[0049] It has well-defined and stable optical constants such as refractive index and dispersion coefficient, which are the basis for optical design and manufacturing.

[0050] 5. Good thermal stability:

[0051] It can maintain the stability of its optical performance and physical structure within a certain temperature range. When the temperature changes, the refractive index, size and other parameters of the optical glass 12 change very little.

[0052] In particular, the material should have a good coefficient of thermal expansion. When the lithium battery is fully charged and discharged, the surface temperature is high. It is necessary to avoid changes in the optical properties or physical structure of the mottled sheet 1 due to the surface temperature of the lithium battery, so as to ensure the accuracy of the measurement results.

[0053] Furthermore, the mottled film 11 and the optical glass 12 should be selected from materials with matching coefficients of thermal expansion to reduce stress caused by thermal expansion mismatch.

[0054] 6. High hardness:

[0055] It is wear-resistant and scratch-resistant. During daily use and processing, it is not easily scratched or worn, thus maintaining the optical properties of its surface and giving the resulting optical system a longer service life.

[0056] 7. Good processability

[0057] Various processing techniques, such as cutting, grinding, and polishing, can be used to create optical glass of various shapes and sizes to meet the testing requirements of lithium batteries of different sizes. Furthermore, during processing, the optical glass 12 maintains high precision, surface quality, and optical properties.

[0058] Specifically, the method for preparing the mottled pattern 1 includes:

[0059] S1. First, the optical glass 12 is cut and polished according to the (length and width) dimensions of the mottled film 11. Then, it is cleaned in an ultrasonic cleaner with organic solvents (such as acetone, ethanol, etc.) to remove surface oil and impurities. Then, it is rinsed with deionized water and dried in a clean environment.

[0060] In some implementation methods, please refer to Figure 1 As shown, the mottled sheet 1 further includes an adhesion layer 13, which is disposed on the surface of the optical glass 12 on the side close to the mottled sheet film 11.

[0061] Accordingly, the preparation method of the mottled pattern 1 includes:

[0062] S11, the dried optical glass 12 substrate is surface treated by forming a uniform, nano-thickness-scale adhesion layer 13 on the substrate surface through chemical coating or physical vapor deposition, so as to enhance the adhesion between the strong adhesive layer and the substrate in step S2.

[0063] In some embodiments, the thickness of the coating layer 13 is 20-80 nm.

[0064] Within this thickness range, the adhesion layer 13 can provide a certain degree of adhesion enhancement, while also reducing the impact of the thickness of the adhesion layer 13 on the optical system of the mottled sheet 1. For example, it can prevent the gap between the mottled sheet film 11 and the optical glass 12 from being too large (due to the influence of the superimposed strong adhesive layer), which affects the flatness of the mottled sheet film 11 and can also control costs.

[0065] In some embodiments, the material of the adhesion layer 13 is silicon dioxide.

[0066] Using silica as the adhesion-enhancing layer 13, combined with appropriate preparation processes, can significantly improve the adhesion between the substrate and the subsequent strong adhesive layer, while maintaining good optical and chemical properties.

[0067] S2, apply or attach strong adhesive to the edges of the optical glass 12 with the strong adhesive layer attached, and then attach the mottled film 11 to the substrate of the optical glass 12 so that the two are horizontally attached.

[0068] Right nowFigure 1 The mottled film 11 and the adhesive layer 13 shown are connected by strong adhesive around their edges.

[0069] In some implementations, heating further crosslinks and cures the super glue.

[0070] Specifically, the heating temperature is 100-150℃, and the heating time is 10-30 minutes.

[0071] In some implementation methods, please refer to Figure 1 As shown, the cloud-patterned sheet 1 further includes a protective layer 14, which is disposed on the surface of the cloud-patterned sheet 1 and is transparent.

[0072] In some embodiments, the protective layer 14 is disposed on the surface of the mottled film 11 on the side away from the optical glass 12.

[0073] Accordingly, the preparation method of the mottled pattern 1 includes:

[0074] S21, a protective layer 14 is formed on the surface of the mottled sheet 1 by means of bonding or coating. The material of the protective layer 14 can be a transparent polymer film. The protective layer 14 covers the surface of the mottled sheet 1 to prevent the mottled sheet 1 from being scratched or contaminated during use.

[0075] The dimensions of the mottled sheet 1 on the plane are adapted to the measured surface of the lithium battery 2. That is, the dimensions of both the optical glass substrate 12 and the mottled sheet film 11 on the plane are set according to the dimensions of the measured surface of the lithium battery 2.

[0076] Example 1

[0077] Please refer to Figure 1 As shown, this utility model embodiment provides a cloud-patterned sheet 1.

[0078] The optical glass 12 substrate has dimensions of 20 cm × 20 cm and a thickness of 2 mm.

[0079] Optical glass 12 was purchased from Qingyong Glass Cutting Shop in Jimei District, Xiamen City.

[0080] Use vernier calipers to measure the thickness in each direction to reduce the deformation of the cloud pattern caused by uneven base thickness and uneven spacing of cloud stripes.

[0081] The mottled sheet film 11 was purchased from Jiudi Microelectronics Technology (Hubei) Co., Ltd. Its thickness is 0.5 mm. The gratings on the mottled sheet film 11 are arranged in concentric circles.

[0082] The grating spacing ε is 150 μm. The widths of the transparent and opaque areas are equal (duty cycle 50%).

[0083] The cloud-patterned sheet 1 includes an additional layer 13.

[0084] Specifically, a uniform silicon dioxide coating layer 13 with a thickness of 50 nm is formed on the surface of the optical glass 12 substrate in the mottled sheet 1 near the mottled sheet film 11 by physical vapor deposition.

[0085] Hot-melt adhesive tape is applied to the periphery of the surface of the optical glass with the adhesion layer. Then, a mottled film is adhered to the optical glass substrate with the adhesive tape, so that the two are horizontally bonded. The adhesive tape is then heated at 120°C for 20 minutes to further cross-link and cure.

[0086] Specifically, the width of the adhesive layer after heating is 1 cm and the thickness is 0.05 mm.

[0087] The cloud-patterned sheet 1 includes a protective layer 14.

[0088] Specifically, a uniform transparent polymer protective film with a thickness of 0.1 mm is formed on the surface of the mottled film 11 away from the substrate of the optical glass 12 by bonding, serving as the protective layer 14.

[0089] Measurement of the height of the spherical crown:

[0090] Please refer to the test system. Figure 3 As shown, replace the sphere with lithium battery 2 in the figure.

[0091] The testing system includes:

[0092] The cloud-patterned sheet 1 is used to be placed horizontally on the surface of the object to be tested (lithium battery 2).

[0093] Camera 3 is positioned above the cloud pattern sheet 1 and is used to photograph the cloud pattern formed on the cloud pattern sheet 1.

[0094] When the camera is positioned vertically (i.e., aligned with the normal direction of the object's surface), the light propagation path is symmetrical, allowing the capture of light reflected or diffracted from the entire object's surface, thus obtaining a complete cloud pattern. Observing the cloud pattern from a vertical position minimizes angular distortion, ensuring the integrity and accuracy of the pattern. Simultaneously, the light intensity distribution on the observed object's surface is more uniform, enabling clear capture of the cloud pattern's contrast.

[0095] Light source 4 is positioned above the cloud pattern sheet 1 and is used to emit light to illuminate the cloud pattern sheet 1, thereby creating a cloud pattern on the cloud pattern sheet 1.

[0096] When incident light shines at a 45° angle, the periodic structure of the grating projects a shadow on the object's surface. If there is a height difference Δh on the object's surface, the shadow will produce a horizontal displacement Δx. Since the incident angle θ = 45° and tanθ = 1, Δx = Δh. That is, the height difference is directly converted into a horizontal displacement.

[0097] Since the brightness of the cloud pattern decreases as the level increases, light source 4 needs to provide sufficient light intensity to ensure the formation of the cloud pattern and the clarity of the cloud pattern obtained in further photography.

[0098] The centers of the camera 3, the light source 4, and the cloud-patterned sheet 1 are located on the same plane.

[0099] The number of cloud-like stripes in the image is obtained by counting the number of cloud-like stripes. .

[0100] The cloud pattern consists of alternating light and dark cloud stripes.

[0101] Specifically, the mottled stripes are counted along the diagonal direction passing through the center of the lithium battery surface.

[0102] The testing methods include:

[0103] Based on the number of cloud-shaped stripes The warpage of the lithium battery was obtained. .

[0104] and The numbers of bright fringes are respectively the number of two rays with opposite directions originating from the center of the lithium battery surface, and the two rays are located on the same straight line.

[0105] The principle behind the moiré pattern sheet 1 and the testing system for measuring the surface warpage of lithium batteries is the shadow moiré method. This method utilizes the projection and occlusion effects of a grating within a geometric optical framework to convert the height variation of an object's surface into a visible moiré pattern. When a reference grating and a shadow grating after the object's surface deformation are superimposed, if their periods are similar but there is a slight displacement, moiré fringes (moiré patterns) will be formed. The spacing of the moiré patterns is much larger than the grating period, thus amplifying the slight displacement and making it easier to observe.

[0106] A sphere with a radius R of 5 cm is placed on a horizontal surface, and then the mottled sheet 1 is placed horizontally on the sphere. The mottled sheet film 11 of the mottled sheet 1 faces downwards and is in direct contact with the sphere.

[0107] Specifically, by setting support structures on both sides of the sphere at the same height as the top of the sphere, the cloud-patterned sheet is placed horizontally on the sphere.

[0108] The cloud-pattern sheet 1 is illuminated by the light source 4, causing a stable cloud pattern to form on the sheet 1. The angle between the line connecting the center of the light source 4 and the center of the cloud-pattern sheet 1 and the normal at the center of the cloud-pattern sheet 1 is 45°.

[0109] Specifically, light source 4 is a spotlight with a brightness of 1000 LM.

[0110] The cloud pattern is photographed using camera 3 to obtain an image. The line connecting the centers of camera 3 and the cloud pattern piece 1 coincides with the normal line at the center of the cloud pattern piece 1.

[0111] Please refer to Figure 4 As shown in the image, there is a dark stripe at the bottom of the sphere with a radius of 15 cm corresponding to the top of the sphere. Counting the dark stripes of the sphere's crown, we get 15 dark stripe stripes (excluding the dark spot in the center, i.e., the dark stripe with a circular center in the cloud pattern).

[0112] It should be noted that in this embodiment of the invention, the counted cloud-like stripes are dark patterns.

[0113] The reason for the dark spot at the center is likely because the curvature of the sphere is much greater than that of the plane, causing the grating to be misaligned by half a period. Therefore, the dark fringes are used for calculations without affecting the accuracy of the optical system.

[0114] The height of the crown:

[0115] Calculated based on the radius R of the sphere: .

[0116] The test system measured the following: .

[0117] The height value of the spherical crown obtained by the testing system is the same as the actual value, indicating that the cloud-patterned sheet 1 has almost no error in the micron-level measurement, and the accuracy can meet the requirements for measuring the surface warp of the lithium battery 2.

[0118] Example 2

[0119] Please refer to Figure 3 As shown, the surface warpage of a 280 Ah lithium battery 2 was measured using the same test system as in Example 1.

[0120] Specifically, the brand of lithium battery 2 is CATL (Contemporary Amperex Technology Co., Limited).

[0121] Please refer to Figure 5 As shown, the left figure is a schematic diagram of the lithium battery 2, where the gray area represents the surface of the lithium battery 2 on which the warpage measurement is performed. In the right figure, the blue part on the gray area represents the mottled sheet 1 placed on the surface of the lithium battery 2.

[0122] It should be noted that the size of the cloud-patterned sheet 1 may be greater than, equal to or smaller than the size of the surface of the lithium battery 2 on which it is placed.

[0123] For example, in some embodiments, the size of the mottled sheet 1 is 32 cm × 32 cm. The size of the surface of the lithium battery 2 is 20.7 cm × 17.3 cm.

[0124] Please refer to the measurement results. Figure 6 As shown.

[0125] It should be noted that in this embodiment of the present invention, the warpage of the lithium battery 2 surface fails to cause the grating to produce a misaligned half-cycle phenomenon. The center of the cloud pattern is a bright spot (the center of the cloud pattern is a circular bright stripe). Alternating light and dark cloud stripes are formed around this bright spot.

[0126] The number of cloud-like stripes in the image is counted along the diagonal direction passing through the center of the surface of lithium battery 2, resulting in a number of bright stripes m=13 and n=10.

[0127] The lithium battery warpage ω is calculated to be 1725 μm based on the above formula.

[0128] The cloud-patterned sheet 1 provided by this invention can detect minute displacement changes and accurately measure the slight warping of the lithium battery 2 surface. This is very important for lithium batteries 2, which have high requirements for flatness, as it helps to detect minute deformation problems, provides accurate measurement data for the production process, and ensures the quality and performance of the lithium battery 2.

[0129] The testing system and method using the moiré pattern sheet 1 can acquire a large amount of test data in a short time, improving testing efficiency. For mass-produced lithium batteries 2, this allows for rapid testing of a large number of products, timely detection of quality problems, and improved production efficiency and product quality. Simultaneously, the testing method is simple to operate, reducing the technical requirements for operators and improving the operability and efficiency of the test.

[0130] The mottled sheet 1 is not limited to measuring the surface warp of the lithium battery 2, but can also be used to measure the surface warp of other objects, especially larger objects.

[0131] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A cloud-patterned pattern, characterized in that, The mottled sheet comprises: a mottled sheet film and optical glass, wherein the edge of the mottled sheet film is adhered to the optical glass; The material of the mottled film is PET or PC; The coefficient of thermal expansion of the optical glass is α 100 / 300℃ 1×10 -5 / K-1×10 -6 / K; The gratings on the mottled film are arranged in concentric circles, and the grating spacing is... It is 120-180 μm; The mottled sheet further includes an adhesion layer, which is disposed on the surface of the optical glass on the side near the mottled sheet film.

2. The cloud-patterned sheet as described in claim 1, characterized in that, The optical glass has a length of 15-25 cm, a width of 15-25 cm, and a thickness of 1.5-2.5 mm.

3. The cloud-patterned sheet as described in claim 1, characterized in that, The thickness of the coating layer is 20-80 nm.

4. The cloud-patterned sheet as described in claim 1, characterized in that, The material of the coating layer is silicon dioxide.

5. The cloud-patterned sheet as described in claim 1, characterized in that, The cloud-patterned sheet further includes a protective layer, which is disposed on the surface of the cloud-patterned sheet and is transparent.

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