Micro-optical element and preparation method therefor, electronic device and Anti-counterfeiting label

Abstract

The present application relates to the technical field of optical elements. Disclosed are a micro-optical element and a preparation method therefor, an electronic device and an anti-counterfeiting label. The micro-optical element, namely a dynamic imaging film, comprises a base layer, and a micro-graphic layer and a micro-lens array layer arranged on two sides of the base layer in the direction of thickness thereof, wherein a plurality of steps having randomly distributed heights are provided inside recesses of the micro-graphic layer, and the plurality of steps may form inside the recesses at least one micro-filling structure having an irregularly shaped opening. The micro-filling structure can function to lock a filling material, e.g., ink, increase the ink filling volume and solve the problem of poor ink filling, thereby facilitating an improvement in the display effect of an imaging pattern.

Description

Micro-optical elements and their fabrication methods, electronic devices, anti-counterfeiting labels

[0001] This application claims priority to Chinese Patent Application No. 202410703927.5, filed on May 31, 2024, entitled "Micro-optical elements and their preparation methods, electronic devices, and anti-counterfeiting labels", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical element technology, and in particular to a micro-optical element and its preparation method, electronic equipment, and anti-counterfeiting label. Background Technology

[0003] A dynamic imaging film is a micro-optical element based on the moiré amplification principle that provides a naked-eye 3D display effect. It is primarily used for product decoration or anti-counterfeiting. Product forms include, but are not limited to, the exterior decoration of various electronic devices such as mobile phones, watches, and tablets, or anti-counterfeiting labels and packaging for documents and goods. For example, referring to Figure 1, a dynamic imaging film 112 can be provided in the back cover 11 of mobile phone 10. Furthermore, as can be seen from the cross-sectional view along the AA direction, the dynamic imaging film 112 can be attached to the inside of the glass cover 110 using optical adhesive 111 as a back cover decoration, thereby enhancing the aesthetics and recognizability of mobile phone 10.

[0004] Figure 2A is a cross-sectional schematic diagram of a dynamic imaging film. As shown in Figure 2A, the dynamic imaging film 112 mainly includes a substrate layer 1122 and a microlens array layer 1123 and a micro-image layer 1121 located on both sides of the substrate layer 1122. The micro-image layer 1121 includes micro-image regions 1121-2 fabricated according to an imaging pattern. Each micro-image region 1121-2 includes a groove 1121a and nano-ink (not shown) filling the groove. Through imaging and moiré magnification of the micro-image regions 1121-2 by the microlens array layer 1123, micro-images at the micrometer scale are magnified to millimeter-scale imaging patterns, and the patterns exhibit a three-dimensional floating or dynamic display effect that changes with the viewing angle.

[0005] Currently, coloring of the micro-image area 1121-2 can be achieved by filling the groove 1121a with nano-ink through a scraping process, thus giving the imaging pattern color. However, the material of the micro-image layer 1121 is generally a photocurable adhesive, and the groove 1121a will deform to a certain extent during the scraping process. Therefore, due to the influence of the surface tension of the ink and the deformation of the groove 1121a during scraping, if the width of the groove 1121a is too large, resulting in a small aspect ratio, poor ink filling in the groove 1121a is likely to occur. This leads to a central void in the lines of the final imaging pattern, which in turn limits the width of the groove 1121a, i.e., limits the maximum line width of the pattern that the dynamic imaging film 112 can display, resulting in poor display effect when used to display large-sized patterns. Summary of the Invention

[0006] To address the aforementioned issues, embodiments of this application provide a micro-optical element and its fabrication method, an electronic device, and an anti-counterfeiting label.

[0007] In a first aspect, embodiments of this application provide a micro-optical element, including a substrate layer and a micro-image layer and a microlens array layer disposed on both sides thereon along its thickness direction; wherein, the micro-image layer includes a micro-image region, the micro-image region includes a groove, the groove having a first depth along the thickness direction; and, the groove is provided with a plurality of steps of different heights, each step having a height greater than or equal to 0 and less than or equal to the first depth, wherein the height of each step is the dimension of each step along the thickness direction; the plurality of steps of different heights form at least one micro-filling structure, the micro-filling structure being used to fill a first material.

[0008] The first material may refer to a nanoscale filler material, such as the ink mentioned in the embodiments of this application.

[0009] The micro-optical element provided in this application embodiment, namely the dynamic imaging film, has a micro-filling structure formed in the groove of its micro-image layer. This micro-filling structure can lock the ink, increase the ink filling amount, and avoid the problem of poor ink filling. As a result, the lines of the imaging pattern of the dynamic imaging film will not have a central hole problem, which can break through the limitation of the maximum line width of the imaging pattern and improve the display effect of the imaging pattern.

[0010] In some embodiments of the first aspect described above, the shape of the groove in the first plane corresponds to the imaging pattern of the micro-text area, the shape of the micro-filling structure on the first plane is an irregular shape, and the first plane is perpendicular to the thickness direction.

[0011] It is understandable that the groove is made according to the actual imaging pattern required. Therefore, the shape of the groove in the first plane matches the imaging pattern of the micro-image area. Furthermore, since the height of the multiple steps in the groove is randomly distributed, the shape of each micro-filling structure formed by different steps in the first plane is irregular, and different micro-filling structures can have different shapes.

[0012] In some embodiments of the first aspect described above, the microtext layer includes a plurality of microtext regions, and at least one of the shape of the grooves in different microtext regions in the first plane and the color of the first material they are filled with is the same; wherein the shape of each groove in the first plane matches the imaging pattern of the corresponding microtext region.

[0013] It is understood that multiple microtext areas in a microtext layer can be used to display the same imaging pattern or different imaging patterns. In some embodiments, the groove shapes of different microtext areas are the same, but the colors of the first material they are filled with are different; or, the groove shapes of different microtext areas are different, but the colors of the first material they are filled with are the same; or, the groove shapes and the colors of the first materials they are filled with are both the same. In other embodiments, the groove shapes and the colors of the first materials they are filled with may all be different.

[0014] In some embodiments of the first aspect described above, the plurality of microtext areas include a first microtext area and a second microtext area, wherein the height distribution of the plurality of steps in the first groove of the first microtext area is different from the height distribution of the plurality of steps in the second groove of the second microtext area.

[0015] It is understood that in the embodiments of this application, the heights of multiple steps within a groove in a single micro-image area are randomly distributed, and the heights of multiple steps within different grooves corresponding to different micro-image areas have different random distribution patterns. Thus, even if the amount of first material filling at different locations within a single groove differs—for example, the amount of first material filling in the micro-filled structure formed by some lower-height steps is slightly higher than that in other step areas—the differences within a single micro-image area can be homogenized for the entire micro-image layer because the heights of multiple steps within different grooves corresponding to different micro-image areas have different random distribution patterns. This results in better color uniformity and consistency of the overall imaging pattern.

[0016] In some embodiments of the first aspect described above, the size of the microfilled structure in the first direction is 0.5 to 3 times the first depth, and the first direction is perpendicular to the thickness direction.

[0017] It can be understood that the maximum depth of each micro-filling structure is the first depth, thus the aspect ratio of each micro-filling structure can be between 0.5 and 3, which improves the aspect ratio of the local area of ​​the groove in the micro-image layer. In this way, during the ink scraping process, because the aspect ratio of the local area of ​​the groove is large, the ink can be locked in, the ink filling amount can be increased, and the lines of the image pattern will not have central voids.

[0018] Secondly, embodiments of this application provide a method for fabricating a micro-optical element, comprising: obtaining a composite pattern, the composite pattern including a micro-image to be fabricated, the micro-image to be fabricated including a plurality of first pixels with different gray values; based on the composite pattern, forming a micro-image layer on one side of a substrate layer along its thickness direction, the micro-image layer including grooves matching the micro-image to be fabricated, and the grooves including a plurality of steps with different heights corresponding one-to-one with the plurality of first pixels with different gray values; forming a microlens array layer on the other side of the substrate layer along its thickness direction to obtain a micro-optical element.

[0019] It is understandable that in the fabrication process of dynamic imaging films, a micro-image layer is formed using a grayscale laser direct-write photoresist process. For example, based on the grayscale value of each first pixel in the composite pattern, a corresponding laser exposure is used to form a step corresponding to each first pixel. The grayscale value range of the first pixel can be [0,1], where data 0 corresponds to a white pixel and the corresponding exposure can be 0; data 1 corresponds to a black pixel and can correspond to the maximum exposure.

[0020] In some embodiments of the second aspect described above, obtaining a composite layout includes: obtaining an initial layout, the initial layout including an initial micro-image, the initial micro-image including multiple second pixels with the same grayscale value; obtaining a random noise image with the same pixel size as the initial layout, the random noise image including multiple third pixels with different grayscale values; processing based on the random noise image and the initial layout to obtain a composite layout; wherein, the grayscale value of each first pixel in the composite layout is determined according to the grayscale value of the second pixel corresponding to each first pixel in the initial micro-image and the grayscale value of the third pixel corresponding to each first pixel in the random noise image.

[0021] It is understandable that traditional methods directly utilize the initial layout to create the microtext layer, while the embodiments of this application first process the initial layout using a random noise image to obtain a composite layout, and then use the composite layout to create the microtext layer. This allows the aforementioned micro-filling structure to be formed in the grooves within each microtext area of ​​the microtext layer. Furthermore, random noise images have strong universality; the same random noise image can be used to prepare dynamic imaging films with different colors or different imaging patterns.

[0022] In some embodiments of the second aspect above, forming a microtext layer on one side of the substrate layer along its thickness direction based on a composite pattern includes: forming the microtext layer directly on the substrate layer using a grayscale laser direct-write photoresist process based on the composite pattern.

[0023] In some embodiments of the second aspect described above, forming a microtext layer on one side of the substrate layer along its thickness direction based on a composite pattern includes: fabricating a microtext layer mold based on the composite pattern; and forming the microtext layer by imprinting the mold onto the substrate layer using a nanoimprinting process.

[0024] It is understood that the micro-image layer in the embodiments of this application can be directly processed on the substrate layer by grayscale laser direct writing photoresist process, or the micro-image layer mold can be pre-processed by grayscale laser direct writing photoresist process, and then the micro-image layer can be imprinted onto the substrate layer by using the mold through nanoimprinting process.

[0025] In some embodiments of the second aspect described above, the method further includes: applying nano-ink to the grooves of the microtexture layer by an ink scraping process.

[0026] It is understood that the dynamic imaging film in this application embodiment mainly relies on filling ink to achieve coloring of the microtext layer. In some embodiments, the color of the final imaging pattern can be changed by changing the color of the ink.

[0027] Thirdly, embodiments of this application provide an electronic device, including a housing, the housing including a light-transmitting layer and the micro-optical element described in the first aspect, the micro-optical element being attached to the light-transmitting layer.

[0028] It is understood that the micro-optical elements in the embodiments of this application can be applied to electronic devices, thereby improving the aesthetics and recognizability of the electronic devices.

[0029] Fourthly, embodiments of this application provide an anti-counterfeiting label, including the micro-optical element described in the first aspect, wherein the anti-counterfeiting label is used to be applied to the surface of an anti-counterfeiting product.

[0030] It is understood that the micro-optical elements in the embodiments of this application can be used as anti-counterfeiting labels in various anti-counterfeiting products. Attached Figure Description

[0031] Figure 1 shows a schematic diagram of a mobile phone 10;

[0032] Figure 2A shows a cross-sectional schematic diagram of a dynamic imaging diaphragm;

[0033] Figure 2B shows a schematic diagram of the scraping process of an imaging unit in a dynamic imaging film;

[0034] Figure 3A shows a cross-sectional view of a dynamic imaging diaphragm 30 according to some embodiments of this application;

[0035] Figure 3B shows a cross-sectional view of an imaging unit 310 according to some embodiments of this application;

[0036] Figure 3C illustrates a schematic diagram of the filling process and filling effect of a groove 301a according to some embodiments of this application;

[0037] Figure 3D shows a three-dimensional schematic diagram of a dynamic imaging diaphragm 30 according to some embodiments of this application;

[0038] Figure 3E shows various top views of the dynamic imaging diaphragm 30 according to some embodiments of this application;

[0039] Figure 3F illustrates various shapes of the step 3011 according to some embodiments of this application;

[0040] Figure 4 shows a schematic diagram of the fabrication process of a dynamic imaging film 30 according to some embodiments of this application;

[0041] Figure 5 illustrates a schematic diagram of obtaining a composite layout according to some embodiments of this application. Detailed Implementation

[0042] The illustrative embodiments of this application include, but are not limited to, a micro-optical element and its preparation method, an electronic device, and an anti-counterfeiting label.

[0043] It is understood that the electronic devices in the embodiments of this application may include, but are not limited to, mobile phones, tablets, laptops, cameras, ultra-mobile personal computers (UMPCs), handheld computers, televisions, walkie-talkies, netbooks, POS machines, personal digital assistants (PDAs), wearable devices, virtual reality devices, smart vehicles, smart robots, industrial equipment, displays, servers, and other devices with appearance decoration or anti-counterfeiting requirements. This application does not impose any restrictions on these.

[0044] As mentioned earlier, dynamic imaging films (hereinafter referred to as films) can be used for the appearance decoration of electronic devices. As shown in Figure 1, the back cover 11 of the mobile phone 10 may include a glass cover plate 110, optical adhesive 111, and film 112 stacked in sequence. Among them, the side of the film 112 facing away from the glass cover plate 110 is also provided with other functional layers 113, including but not limited to optical coating layers, screen printing layers, etc.

[0045] Understandably, in other electronic device applications, the film can also be attached to the dial of a watch as a decorative element. Alternatively, when used as an anti-counterfeiting label, the film can be embedded inside a document or tag, and a translucent material can be applied to the surface of the film to ensure the clarity of the image while protecting it from wear and tear.

[0046] The following description of the membrane 112 is based on Figure 2A. As shown in Figure 2A, the microtext layer 1121 and the microlens array layer 1123 in the membrane 112 are disposed on both sides of the substrate layer 1122 along the thickness direction (X direction shown in each figure).

[0047] The microimage layer 1121 includes a blank area 1121-1 and a microimage area 1121-2. The microimage areas of the microimage layer 1121 correspond one-to-one with the microlenses 11231 of the microlens array layer 1123. After being magnified and imaged by the microlens array layer 1123, the different microimage areas together constitute the imaging pattern of the film. The image features of the imaging pattern can be a combination of one or more effects such as sinking, floating, scaling, rotation, orthogonal movement, and motion deformation. Sinking and floating refer to the three-dimensional effect of the image observed by the user appearing to float or sink into the paper. Orthogonal movement refers to the image observed moving in a direction perpendicular to the user's viewing angle. Motion deformation refers to changes in size and shape of the image observed by the user during movement.

[0048] It can be understood that the diaphragm 112 can also be regarded as being composed of multiple imaging units 1120. As shown in the dashed box in Figure 2A, a single imaging unit 1120 may include a single micro-image area 1121-2 and a single microlens 11231. The following description will continue with a single imaging unit 1120 as an example.

[0049] For example, please refer to Figure 2B. Taking the imaging pattern of the micro-image area 1121-2 as an "A" shape as an example, Figure 2B shows a schematic diagram of the scraping process of the imaging unit 120 and the filling effect of the groove 1121a. It can be understood that the shape of the groove 1121a matches the imaging pattern of the micro-image area 1121-2, that is, the shape of the groove 1121a in the plane perpendicular to the X direction (the first plane mentioned in this application) is "A".

[0050] As shown in Figure 2B, colored liquid ink with a particle size on the order of hundreds of nanometers is filled into the interior of a groove 1121a with a depth of several micrometers using a scraper 20. Since the material of the microtexture layer 1121 is generally a photocurable adhesive, the groove 1121a will deform to a certain extent during the scraping process. Therefore, due to the influence of the surface tension of the ink and the deformation of the groove 1121a during the scraping process, when the width of the groove 1121a is too large, resulting in a small aspect ratio, the ink scraped to the center of the groove 1121a is easily carried away again by the scraper 20. This results in a situation where the ink thickness in the center of the groove 1121a, i.e., the "A" shape, is relatively thin, while the ink thickness at the edges is relatively large.

[0051] It should be noted that the depth mentioned in this application can refer to the thickness in the X direction. The width mentioned in this application can refer to the dimension in the Y direction as shown in the figures, where the Y direction is perpendicular to the X direction. The aspect ratio is the ratio between the depth and the width of the groove 1121a.

[0052] It is understandable that the color depth of the imaging pattern is related to the amount of nano-ink filling. This phenomenon of poor ink filling can lead to central voids in the lines of the final imaging pattern. As shown in Figure 2B, the edges of the "A"-shaped pattern lines are darker, while the interior is lighter, affecting the color uniformity of the pattern. Currently, to avoid central voids in the lines of the imaging pattern, the width of the grooves 1121b in the microtexture layer 1121 is usually limited, which limits the maximum line width of the pattern that the dynamic imaging film can display.

[0053] Based on this, embodiments of this application propose a dynamic imaging film (i.e., the micro-optical element mentioned in this application). Specifically, step units are provided within the grooves of the micro-image layer. Each step unit includes multiple steps with randomly distributed heights, where the maximum height of the step can be the depth of the groove, and the minimum height can be 0. Thus, multiple steps can form at least one micro-pit structure with an irregularly shaped opening inside the groove (i.e., the micro-filling structure mentioned in this application). The walls of this micro-pit structure can provide support during the coating process, preventing the ink from being scraped away by the scraper due to excessive deformation of the groove. Therefore, the micro-pit structure can lock in the ink, increase the ink filling amount, and avoid the problem of poor ink filling. Consequently, the lines of the imaging pattern of the dynamic imaging film will not have central voids, ensuring the uniformity of the imaging pattern color and overcoming the limitation on the maximum line width of the imaging pattern.

[0054] Please refer to Figure 3A, which is a cross-sectional view of a dynamic imaging diaphragm 30 provided in an embodiment of this application. The dynamic imaging diaphragm 30 includes a microtexture layer 301, a substrate layer 302, and a microlens array layer 303. It can be understood that the layer structure of the diaphragm 30 is the same as or similar to that of the diaphragm 112, and the diaphragm 30 can also be regarded as being composed of multiple imaging units 310. The difference is that multiple steps 3011 with a high degree of random distribution are provided in the grooves 301a of the microtexture layer 301 in the diaphragm 30.

[0055] It should be noted that each of the multiple imaging units 310 can form an imaging pattern. Different imaging units 310 can form the same imaging pattern or different imaging patterns. Multiple imaging patterns formed by multiple imaging units 310 can be combined to form an imaging pattern that matches the size of the diaphragm 30.

[0056] The following description uses a single imaging unit 310 as an example. Please refer to FIG3B, which is a cross-sectional view of an imaging unit 310 provided in an embodiment of this application.

[0057] As shown in Figure 3B, multiple steps 3011 with randomly distributed heights are provided within the groove 301a, meaning the heights of the steps 3011 are not entirely the same. The height of each step 3011 can range from 0 to x1, where x1 represents the maximum depth of the groove 301a. Furthermore, the width of each step 3011 along the Y direction is the same. For example, the dimension of the groove 301a along the Y direction in Figure 3B is equivalent to the sum of the widths of 11 steps 3011 along the Y direction. The height of the third step from the left is x1, and the height of the fifth step is 0. Since the height of the fifth step is 0, Figure 3B exemplarily shows 10 steps 3011.

[0058] Among the multiple steps 3011, steps 3011 whose height is flush with the depth of grooves 301a can be used to form micro-pit structures. For example, in Figure 3B, the third step 3011 to the left sidewall of groove 301a forms micro-pit structure 301a-1, and the third step 3011 to the right sidewall of groove 301a forms micro-pit structure 301a-2. It can be understood that the bottom of micro-pit structure 301a-1 includes the tops of the first step and the second step. The bottom of micro-pit structure 301a-2 includes the tops of the fourth to eleventh steps.

[0059] For example, taking the shape of the groove 301a in the first plane as "A"-shaped, please refer to Figure 3C. Figure 3C is a schematic diagram of the filling process and filling effect of the groove 301a provided in an embodiment of this application. Compared with the groove 1121a in the diaphragm 112 shown in Figure 2B, the groove 301a in the diaphragm 30 can lock the ink through the micro-pit structure 301a-1 and micro-pit structure 301a-2, increasing the ink filling amount, so that the lines of its imaging pattern will not have a central void problem, breaking through the limitation of the maximum line width of the imaging pattern, which is conducive to realizing more complex imaging patterns.

[0060] The structure of groove 301a will be further explained below with reference to Figure 3B.

[0061] As shown in Figure 3B, the maximum depth of groove 301a is x1. It can be understood that the depth of groove 301a is different on different cross-sections. In the cross-section shown in Figure 3B, the depth of groove 301a is less than x1. For example, the range of x1 can be 1 to 10 micrometers (μm).

[0062] Secondly, the groove 301a can have different widths on different cross-sections. For example, on the cross-section shown in Figure 3B, the width of the groove 301a is equivalent to the sum of the widths of 11 steps 3011. On other cross-sections, the width of the groove 301a can be equivalent to the sum of the widths of fewer or more steps 3011. In other words, the width of the groove 301a on a specific cross-section is equivalent to the sum of the widths of multiple steps 3011 arranged along the width direction (Y direction shown in each figure) on that specific cross-section.

[0063] Furthermore, this application does not limit the width of each step 3011. Since the microtext layer 301 or its preparation mold is generally prepared by a grayscale laser direct writing photoresist process, the width of each step is related to the resolution of the grayscale laser direct writing device. For example, the width of each step 3011 can be between 0.1 and 1 micrometer (μm).

[0064] Referring again to Figure 3B, for a groove 301a with a maximum depth of x1, the height of each step 3011 inside it ranges from 0 to x1. Furthermore, multiple steps 3011 with randomly distributed heights can form micro-pit structures with irregular opening shapes inside the groove 301a, such as micro-pit structure 301a-1 and micro-pit structure 301a-2. The irregular opening shape means that the shape on the first plane is irregular.

[0065] In some embodiments, the width y1 of each micropit structure can be between 0.5x1 and 3x1. Correspondingly, the aspect ratio of each micropit structure can be between 0.5 and 3.

[0066] It is understandable that by adding randomly distributed steps 3011 inside the groove 301a, the irregular micro-pit structure composed of the steps 3011 can improve the aspect ratio of the local area of ​​the groove 301a in the micro-image layer 301. Thus, during the coating process of the nano-ink, the larger aspect ratio of the local area of ​​the groove 301a can lock in the ink, and the pit walls of the micro-pit structure can provide support during coating, preventing excessive deformation of the groove 301a and preventing the ink from being carried away by the scraper again. This increases the ink filling amount, ensuring that the lines of the imaged pattern do not have central voids.

[0067] The structure of diaphragm 30 will be further explained below with reference to Figures 3D and 3E. Figure 3D is a three-dimensional schematic diagram of diaphragm 30. Correspondingly, Figure 3A can be a cross-section along the AA direction in Figure 3D, and Figure 3E shows various top views of diaphragm 30 along the X direction.

[0068] Referring again to Figure 3A, the diaphragm 30 may include multiple imaging units 310, wherein the imaging pattern and pattern color of each imaging unit 310 may be the same or different. It is understood that if the imaging patterns of two imaging units 310 are different, then the shapes of the micro-image areas 1121-2 and the grooves 301a in the first plane of the two imaging units 310 will be different. The micro-image areas 1121-2 and the grooves 301a are both fabricated based on the final imaging pattern of each imaging unit 310. Furthermore, the pattern color of each imaging unit 310 is also the color of the ink (an example of the first material of this application) filling the groove 301a of that imaging unit.

[0069] For example, taking the microtext layer 301, which includes 16 microtext areas 1121-2, as shown in Figure 3E(a), the imaging patterns and colors corresponding to each microtext area 301-1 are the same, all being "A" shapes. The same fill pattern indicates that the pattern colors are the same. As shown in Figure 3E(b), the imaging patterns of the four microtext areas 301-1 in the first column and the four microtext areas 301-1 in the third column are all "A" shapes with the same pattern color. The imaging patterns of the four microtext areas 301-1 in the second column and the four microtext areas 301-1 in the fourth column are all "B" shapes with the same pattern color. The "A" and "B" shapes are filled with different fill patterns, indicating that their pattern colors are different. As shown in Figure 3E(c), the imaging patterns of each micro-image area 301-1 are the same, all being "A" shaped. However, the pattern colors of the micro-image areas 301-1 in the first and third columns are different from those of the micro-image areas 301-1 in the second and fourth columns. As shown in Figure 3E(d), the pattern colors of each micro-image area 301-1 are the same, but the imaging patterns of the micro-image areas 301-1 in the first and third columns are all "A" shaped, unlike the "B" shaped imaging patterns of the micro-image areas 301-1 in the second and fourth columns.

[0070] In some embodiments, if the imaging patterns of two micro-image areas 301-1 are the same, the corresponding two grooves 301a may have the same number of steps 3011. However, the height distribution of the multiple steps 3011 in the two grooves 301a is different. For example, in the cross-section shown in FIG3A, the imaging patterns corresponding to the four grooves 301a arranged along the X direction are the same, but the height distribution of the 11 steps 3011 in different grooves 301a in this cross-section is different. Specifically, the height of the first step 3011 in each groove 301a is not exactly the same, the height of the second step 3011 in each groove 301a is different from each other, and the same applies to the steps 3011 at other corresponding positions, which will not be described in detail here.

[0071] It is understandable that if the imaging patterns of the two micro-image areas 301-1 are different, then the number of steps 3011 and the height distribution of the steps 3011 within the corresponding two grooves 301a will also be different. For example, please refer to Figures 3E(a) and (b), which show two types of grooves 301a corresponding to the “A” and “B” imaging patterns, respectively. Each small square inside the groove can represent a step 3011. Obviously, the shapes of the two grooves 301a corresponding to the “A” and “B” patterns are different, and similarly, the height distribution of the steps 3011 within the corresponding two grooves 301a is also different.

[0072] In some embodiments, if the pattern colors of the two microtext areas 301-1 are different, the corresponding two grooves 301a may have the same number of steps 3011, and the height distribution of the multiple steps 3011 in the two grooves 301a may be the same. For example, referring to Figure 3E(c), the pattern colors of the microtext areas in the first column and the first row of the second column are different, and both can adopt the “A”-shaped grooves 301a shown in Figure 3E(a).

[0073] It is understandable that for the same micro-image region 301-1, the ink filling amount varies at different positions within the groove 301a due to the different heights of the multiple steps 3011 within the groove 301a. For example, in the cross-section shown in Figure 3B, the ink filling amount in the micro-pit structure 301a-2 is greater than that in the micro-pit structure 301a-1. However, due to the randomness of the height distribution of the multiple steps 3011, the spatial distribution difference of ink filling amount within different micro-image regions 301-1 also varies. For an imaging pattern jointly composed of magnified images of different micro-image regions 301-1, the random distribution of the step heights 3011 can homogenize the differences in nano-ink filling amount within the grooves 301a of each micro-image region 301-1, making the color depth of the final imaging pattern more consistent.

[0074] For example, as shown in Figure 3E(a), the ink filling amount varies at different locations within a single "A" shape. However, due to the different height distribution of the steps 3011 within each "A" shape, the overall ink filling amount is uniform for the imaging pattern composed of 16 "A" shapes. Therefore, the random distribution of step heights can form an irregular micro-pit structure, which can then homogenize the differences in the amount of nano-ink filling within the grooves of different micro-image areas, thereby improving the color uniformity and consistency of the overall imaging pattern.

[0075] In some embodiments, the shape of each step 3011 includes, but is not limited to, any one of a cube, cuboid, cylinder, sphere, cone, triangular pyramid, and square pyramid. For example, as shown in FIG3F(a), each step 3011 within the groove 301a can be a cube or a cuboid. As another example, as shown in FIG3F(b), each step 3011 within the groove 301a can be a cylinder.

[0076] In some embodiments, multiple steps 3011 are laid out in each groove 301a. For example, as shown in (a) and (b) of FIG3F, multiple steps 3011 are laid out in a flat manner to form a cuboid array or a cylindrical array.

[0077] In some embodiments, multiple steps 3011 within each groove 301a can be stacked, for example, as shown in (a) and (c) of FIG3F, a pyramid structure is formed by stacking a certain number of steps 3011, and multiple pyramid structures form a pyramid array within the groove 301a.

[0078] In some embodiments, the microtext layer 301 may be fabricated directly on the substrate layer 302 using a grayscale laser direct-write photoresist process. Alternatively, in other embodiments, the microtext layer 301 is imprinted onto the substrate layer 302 based on a pre-fabricated microtext layer mold. The material of the substrate layer 302 may include, but is not limited to, polyester terephthalate (PET), polyvinyl chloride (PVC), and polyethylene (PE).

[0079] In some embodiments, as shown in FIG3D, the microlens array layer 303 may include a spherical microlens array. Alternatively, in other embodiments, the microlens array layer 303 may also include a columnar microlens array extending along the Z direction.

[0080] The preparation method of membrane 30 is described below with reference to Figure 4. As shown in Figure 4, the method includes the following steps S41 to S43:

[0081] S41: Obtain the composite layout, which includes the micro-text image to be created.

[0082] In the actual preparation process, the composite pattern is imported into the grayscale laser direct writing equipment. The grayscale laser direct writing equipment can make micro-text layers or its molds based on the micro-text images to be made in the composite pattern.

[0083] The micro-image to be created includes multiple first pixels with different gray values. The gray value range of each first pixel is [0,1], where data 0 corresponds to a white pixel and data 1 corresponds to a black pixel.

[0084] S42: Based on the composite pattern, a microtext layer 301 is formed on one side of the base layer 302 along its thickness direction.

[0085] In some embodiments, the microtext layer 301 can be directly fabricated on the substrate layer 302 using a grayscale laser direct-write photoresist process.

[0086] In some embodiments, the micro-image photoresist stencil processed by the grayscale laser direct writing equipment can also be made into a mold, and the micro-image layer 301 can be formed by imprinting on the substrate layer 302 using the mold through a nanoimprinting process.

[0087] During the processing of the microtext layer 301 or its mold, the composite pattern is imported into a grayscale laser direct writing device. The grayscale values ​​of different first pixels in the composite pattern correspond to different laser exposure levels. Among them, the value point 1 corresponds to the maximum exposure level, and the value point 0 corresponds to an exposure level of 0. If the grayscale laser direct writing photoresist process is directly processed on the substrate layer 302, after development, the microtext layer 301 is formed on one side of the substrate layer 302, and multiple randomly distributed steps 3011 are formed at the bottom of the groove 301a of the microtext layer 301.

[0088] After the microtext layer 301 is fabricated on the substrate layer 302, colored nano-ink is applied to the grooves of the microtext layer 301 by an ink scraping process.

[0089] S43: A microlens array layer 303 is formed on the other side of the substrate layer 302 along its thickness direction to obtain a film 30.

[0090] It is understood that a microlens array layer 303 matching the microtexture layer 301 is formed on the other side of the substrate layer 302, and the film 30 presents an magnified imaging pattern through the moiré amplification effect.

[0091] The following describes one method for obtaining the aforementioned composite map.

[0092] In some embodiments, the above-mentioned composite layout can be designed through the following steps S411 to S413:

[0093] S411: Obtain the initial map.

[0094] The initial pattern can be created based on the final imaging pattern to be formed by the membrane 30. The initial pattern includes an initial microtext image, which includes multiple second pixels with the same grayscale value.

[0095] The following section uses the letter "A" as an example to illustrate the design process of the composite pattern and the fabrication process of the microtext layer 301, taking the imaging pattern of the membrane 30 as an example and referring to Figure 5.

[0096] For example, an initial layout 501 as shown in Figure 5 can be created based on the target imaging pattern "A". The black area is the initial microtext image, that is, the microtext area, where the value of each second pixel is 1. The area outside the microtext area is a blank area, where the value of each second pixel is 0.

[0097] It is understandable that the microtext layer 1121 shown in Figure 2A can be fabricated based on the initial layout using a grayscale laser direct writing photoresist process. Since the grayscale value of the second pixel in the initial microtext image is consistent, only a groove 1121a with a flat bottom or consistent depth can be formed.

[0098] S412: Obtain a random noise image with the same pixel size as the initial layout.

[0099] The random noise image includes multiple third pixels with different gray values. Specifically, the random noise image is composed of third pixels with gray values ​​ranging from [0,1].

[0100] For example, as shown in FIG5, a random noise image 502 of the same size as the initial layout 501 is obtained.

[0101] S413: Process the random noise image and the initial layout to obtain a composite layout.

[0102] In the composite image, the grayscale value of each first pixel is determined based on the grayscale value of the second pixel corresponding to each first pixel in the initial micro-image and the grayscale value of the third pixel corresponding to each first pixel in the random noise image. For example, the grayscale value of the second pixel at the same position can be directly ANDed with the grayscale value of the third pixel to obtain the grayscale value of the first pixel at the corresponding position.

[0103] For example, as shown in Figure 5, a pixel-by-pixel AND operation is performed on the initial layout 501 and the random noise image 502 to obtain a composite layout 503. In the composite layout 503, the interior of the "A"-shaped micro-image is filled with a random noise pattern. Furthermore, irregularly shaped and sized speckle patterns 503a (white patches) are formed. These speckle patterns 503a correspond to the shape of the micro-pit structure within the first plane; therefore, the width of the speckle can be between 0.5x1 and 3x1, where x1 is the maximum depth of the pit.

[0104] It should be noted that using the same size as the initial layout image can improve the randomness of the grayscale values ​​of each first pixel in the final composite layout. In other embodiments, the size of the random noise image can be smaller or larger than the size of the initial layout image.

[0105] For example, in some embodiments, as shown in Figure 3E(a), if a composite image is to be created that includes multiple imaging units 310 with identical imaging patterns and colors, the size of the random noise image can be the same as the initial image, thus ensuring good imaging uniformity of the 16 "A" shapes. As shown in Figure 3E(b), if a composite image is to be created with multiple imaging units 310 and different imaging patterns or colors, the random noise image can be reused in different imaging units 310. For example, the width of the random noise image can be the same as the width of a single column of microtext area, and the length (dimension along the Z direction) can be the same as the length of four rows of microtext areas. The first and second columns of microtext areas reuse the same random noise image, as do the third and fourth columns. Similarly, as shown in Figure 3E(c), since the patterns of the first and second columns of microtext areas are different, the same random noise image can be reused. As shown in Figure 3E(d), since the imaging patterns of the first and second microtext areas are different, the same random noise image can be reused.

[0106] In summary, this application proposes a dynamic imaging film 30 based on a micro-pit structure to improve the filling amount of nano-ink. By adding multiple steps 3011 with randomly distributed heights inside the micro-texture groove 301a, the micro-pit structure composed of multiple steps 3011 can improve the aspect ratio of the local area of ​​the micro-texture groove. Thus, during nano-ink coating, the micro-pit structure can lock the nano-ink, increasing the ink filling amount, thereby effectively solving the problem of central voids in large-size imaging patterns of dynamic imaging films. This can relax the industry's upper limit on the line width of dynamic film patterns, enabling the processing of films with more complex imaging patterns.

[0107] Furthermore, since the height distribution of the steps 3011 within each groove 301a is random, the morphology and distribution of the micro-pit structure they form are also irregular, which can prevent the ink filling amount from changing periodically and ensure the uniformity of the color depth of the imaging pattern of the dynamic imaging film 30.

[0108] Furthermore, for other dynamic imaging films with different colors or imaging patterns than film 30, the random noise image of the micro-image layer 301 in film 30 during the preparation of the composite pattern can be reused. Only the color of the filling ink or the groove contour (initial pattern) design needs to be changed. The random noise image has strong universality and can be used for the design of dynamic imaging films with different colors or imaging patterns, which is beneficial to accelerating the mass production of dynamic imaging films.

[0109] It is understood that in other micro-optical elements besides dynamic imaging films, if there are grooves that need to be filled with a medium, the groove 301a in the embodiment of this application can be used as a reference.

[0110] It should be noted that in the examples and description of this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0111] Although this application has been illustrated and described with reference to certain preferred embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made thereto without departing from the scope of this application.

Claims

1. A micro-optical element, characterized by It includes a base layer and microtext layers and microlens array layers disposed on both sides of it along its thickness direction; wherein, The microtext layer includes microtext areas, each microtext area including a groove, the groove having a first depth along the thickness direction; and... The groove is provided with multiple steps of different heights, each step having a height greater than or equal to 0 and less than or equal to the first depth, wherein the height of each step is the dimension of each step along the thickness direction; The plurality of steps of different heights form at least one micro-filling structure, which is used to fill the first material.

2. The micro-optical element according to claim 1, characterized in that, The shape of the groove in the first plane corresponds to the imaging pattern of the micro-image area, and the shape of the micro-filling structure on the first plane is irregular. The first plane is perpendicular to the thickness direction.

3. The micro-optical element according to claim 2, characterized in that, The microtext layer includes multiple microtext regions, and, The grooves in the different micro-text areas have at least one of the same shape in the first plane and the same color of the first material they are filled with; The shape of each groove in the first plane matches the imaging pattern of the corresponding micro-image area.

4. The micro-optical element according to claim 1 or 3, characterized in that, The plurality of micro-text areas include a first micro-text area and a second micro-text area, wherein, The height distribution of multiple steps in the first groove of the first micro-image area is different from the height distribution of multiple steps in the second groove of the second micro-image area.

5. The micro-optical element according to any one of claims 1-3, characterized in that, The microfilled structure has a dimension of 0.5 to 3 times the first depth in a first direction, and the first direction is perpendicular to the thickness direction.

6. A method for fabricating a micro-optical element, characterized in that, include: Obtain a composite layout, wherein the composite layout includes a micro-image to be created, and the micro-image to be created includes multiple first pixels with different grayscale values; Based on the composite pattern, a microtext layer is formed on one side of the base layer along its thickness direction. The microtext layer includes a groove that matches the microtext to be made, and the groove includes multiple steps of different heights that correspond one-to-one with the multiple first pixels with different gray values. A microlens array layer is formed on the other side of the substrate layer along its thickness direction to obtain the micro-optical element.

7. The preparation method according to claim 6, characterized in that, The acquisition of the composite layout includes: Obtain an initial layout, the initial layout including an initial micro-image, the initial micro-image including multiple second pixels with the same grayscale value; Obtain a random noise image with the same pixel size as the initial layout, wherein the random noise image includes multiple third pixels with different gray values; The composite layout is obtained by processing the random noise image and the initial layout. The grayscale value of each first pixel in the composite image is determined based on the grayscale value of the second pixel corresponding to each first pixel in the initial micro-image and the grayscale value of the third pixel corresponding to each first pixel in the random noise image.

8. The preparation method according to claim 6, characterized in that, The step of forming a microtext layer on one side of the base layer along its thickness direction based on the composite layout includes: Based on the composite pattern, the micro-image layer is formed directly on the substrate layer using a grayscale laser direct-write photoresist process.

9. The preparation method according to claim 6, characterized in that, The step of forming a microtext layer on one side of the base layer along its thickness direction based on the composite layout includes: Based on the composite layout, a micro-image layer mold is fabricated; The microtext layer is formed by imprinting the mold onto the substrate layer using a nanoimprinting process.

10. The preparation method according to claim 8 or 9, characterized in that, Also includes: Nano-ink is applied into the grooves of the micro-texture layer using an ink scraping process.

11. An electronic device, characterized in that, The device includes a housing, the housing comprising a light-transmitting layer and a micro-optical element as described in any one of claims 1-5, the micro-optical element being attached to the light-transmitting layer.

12. An anti-counterfeiting label, characterized in that, The product includes the micro-optical element as described in any one of claims 1-5, wherein the anti-counterfeiting label is used to be affixed to the surface of the anti-counterfeiting product.

Images