A composite structure, system, identification method and preparation method of identifiable double-layer two-dimensional code

Abstract

The application discloses a composite structure, system, identification method and preparation method of identifiable double-layer two-dimensional codes, relates to the technical field of information storage and identification, and has the technical scheme as follows: a base material, a first two-dimensional code layer formed by a first color region with a first reflectivity and a second color region with a second reflectivity, a ratio of the first reflectivity to the second reflectivity being greater than 4:1, a transparent isolation layer covering the first two-dimensional code layer, a second two-dimensional code layer formed by a white region and a third color region and arranged on the transparent isolation layer, the transmittance of the white region and the third color region in a preset auxiliary light wave band being greater than 70%, and an optical reflectivity difference between the white region and the third color region being less than 20% of an average reflectivity value.The application realizes the dual anti-fake and information hiding effect that apparent information is visible under natural light and hidden information is readable under auxiliary light, and the two layers of information are completely independent, do not interfere with each other, and have high anti-fake strength.

Description

Technical Field

[0001] This invention relates to the field of information storage and recognition technology, and more specifically, to a composite structure, system, recognition method, and preparation method for recognizing dual-layer QR codes. Background Technology

[0002] QR codes, as a highly efficient information carrier, have been widely used in product traceability, digital payments, advertising, marketing, and anti-counterfeiting authentication. With the deepening of application scenarios, the market has placed higher demands on the information capacity and security and anti-counterfeiting performance of QR codes. Currently, the mainstream solution is still to print an independent QR code pattern on a single carrier surface. This single-layer information carrier structure is simple, but its information storage capacity is fixed and it is extremely easy to copy, making it difficult to meet the needs of complex application scenarios such as high-end anti-counterfeiting and layered information verification.

[0003] To enhance information carrying capacity and anti-counterfeiting levels, the industry has attempted to develop multi-layer information carrier technologies. One existing technology involves printing two different QR code patterns sequentially on a substrate, utilizing the partial translucency of the upper ink layer to attempt to simultaneously present both layers of information under specific lighting conditions. However, this technology often faces a critical bottleneck: because the two patterns overlap physically, when reading information from one layer, the other pattern appears simultaneously as strong background noise or interference, leading to decoding failure or information confusion. For example, if the upper pattern is translucent but uneven under a light source, its residual texture will severely degrade the image quality of the lower QR code. Another approach uses complex microstructures or special photochromic materials, but these are costly to manufacture and involve complex processes, making large-scale application in conventional printed materials difficult.

[0004] Therefore, how to research and design a composite structure, system, recognition method, and preparation method for recognizing a two-layer QR code that can overcome the above-mentioned defects is an urgent problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a composite structure, system, identification method, and preparation method for recognizing dual-layer QR codes. This invention fundamentally achieves a dual anti-counterfeiting and information hiding effect from a physical structure perspective, where the apparent information is visible under natural light and the hidden information is readable under auxiliary light. Furthermore, the two layers of information are completely independent and do not interfere with each other, resulting in high anti-counterfeiting strength.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: Firstly, a composite structure capable of recognizing dual-layer QR codes is provided, comprising: Substrate; The first QR code layer is disposed on the surface of the substrate and is formed by a first color region having a first reflectivity in a preset auxiliary light band and a second color region having a second reflectivity, wherein the ratio of the first reflectivity to the second reflectivity is greater than 4:1. A transparent isolation layer covers the first QR code layer; The second QR code layer is disposed on the transparent isolation layer and is formed by a white area and at least one third color area; The difference in optical properties between the white area and the third color area in the visible light band allows them to together form a QR code pattern that can be recognized by a standard visible light camera. Furthermore, the transmittance of both the white region and the third color region in the preset auxiliary light band is greater than 70%, and the difference in optical reflectance between the two in the preset auxiliary light band is less than 20% of their average reflectance.

[0007] Furthermore, the preset auxiliary light band is a near-infrared light band with a center wavelength of 850nm±20nm.

[0008] Furthermore, the first color area is formed by an ink containing titanium dioxide, and the second color area is formed by an ink containing carbon black.

[0009] Furthermore, the ink used in the white area contains hollow polymer microspheres as a white pigment.

[0010] Furthermore, the ink used in the third color region contains phthalocyanine blue pigment and transparent nano-silica scattering agent.

[0011] Secondly, a system capable of recognizing dual-layer QR codes is provided, including: A composite structure capable of recognizing dual-layer QR codes as described in any of the first aspects; The identification device includes a light source module for emitting the preset auxiliary light band, and an image acquisition and processing module for acquiring an image of the composite structure under the illumination of the preset auxiliary light band and identifying the first QR code layer.

[0012] Furthermore, the image acquisition and processing module includes an image sensor with the infrared cutoff filter removed, and a narrowband filter located in front of the image sensor that matches the preset auxiliary light band.

[0013] Thirdly, a method for recognizing a composite structure of a two-layer QR code is provided as described in any one of the first aspects, comprising the following steps: Under visible light conditions, an image of the composite structure is acquired, and the second QR code layer is decoded; Images of the composite structure were acquired under a preset auxiliary light illumination environment; Background correction processing is performed on the image acquired under the preset auxiliary light to suppress residual signals of the second QR code layer pattern; The image after background correction is binarized and decoded to identify the first QR code layer.

[0014] Furthermore, the background correction process includes subtracting the background image obtained through large kernel median filtering from the original image.

[0015] Fourthly, a method for preparing a composite structure capable of recognizing a dual-layer QR code is provided as described in any one of the first aspects, comprising the following steps: The first QR code layer is formed on the substrate by screen printing using first color ink and second color ink; A transparent optical adhesive layer is coated on the first QR code layer, and after curing, the transparent isolation layer is formed. The second QR code layer is formed on the transparent isolation layer by screen printing using white ink and a third color ink; The white ink and the third color ink are configured to satisfy the following: in the visible light band, both have sufficient covering power to cover the underlying pattern; in the preset auxiliary light band, both have a transmittance greater than 70%, and the difference in optical reflectance is less than 20% of their average reflectance.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a composite structure capable of recognizing dual-layer QR codes. By designing a composite structure comprising a second QR code layer with specific optical properties, a high-contrast first QR code layer, and a transparent isolation layer, the white and third color regions of the second QR code layer exhibit significant optical differences in the visible light band, forming a surface QR code that can be recognized by ordinary devices. Simultaneously, these two layers are configured in a preset auxiliary light band to satisfy a transmittance greater than 70% and a reflectance difference less than 20% of their average value. This ensures that when illuminated by auxiliary light, the second QR code layer becomes transparent due to its high transmittance and forms an optically uniform background due to its extremely low reflectance difference, thus no longer interfering with imaging. At this time, the high-contrast pattern of the first QR code layer is clearly displayed and recognized. This invention fundamentally achieves a dual anti-counterfeiting and information hiding effect from a physical structure perspective, where the apparent information is visible under natural light and the hidden information is readable under auxiliary light. Furthermore, the two layers of information are completely independent and do not interfere with each other, resulting in high anti-counterfeiting strength.

[0017] 2. This invention designs the preset auxiliary light band as near-infrared light with a center wavelength of 850nm±20nm, and uses titanium dioxide and carbon black, hollow polymer microspheres for the white surface layer, and phthalocyanine blue pigment and transparent nano-silica scattering agent as the third color. 850nm near-infrared light is a band that silicon-based image sensors are sensitive to and that experiences less environmental interference. Titanium dioxide and carbon black can provide a reflection contrast ratio of over 8:1 in this band, laying a solid foundation for underlying recognition. Hollow polymer microspheres and phthalocyanine blue pigment inherently have weak absorption in this band, naturally possessing high transmission potential. The introduction of transparent nano-silica provides the basic conditions for precisely controlling the scattering properties of the cyan ink to match the reflectivity of the white ink. This transforms the abstract optical condition of high transmission and low reflection difference into a quantifiable, adjustable, and producible ink formulation and process parameters, thereby ensuring the stability and economy of the technical solution and enabling large-scale application in the field of printing anti-counterfeiting.

[0018] 3. This invention constructs a complete dual-layer information reading system by integrating a composite structure with a dedicated identification device. The 850nm near-infrared light emitted by the light source module is precisely matched with the optical characteristics of the composite structure. In the image acquisition and processing module, the sensor with the infrared cutoff filter removed ensures sensitivity to this wavelength of light, while the added 850nm narrowband filter strongly suppresses stray light interference such as ambient visible light. This allows the sensor to receive almost only the effective signal carrying the underlying information excited by the system's own light source, ensuring that even in complex lighting environments, it can stably and accurately capture clear underlying QR code images, thus improving the practicality and anti-interference capability of the entire technical solution.

[0019] 4. This invention employs conditional acquisition, background correction, and binarization decoding processing. In the original image acquired under auxiliary light, the underlying QR code to be extracted is a fine pattern with high spatial frequencies, while undesirable surface residual signals and uneven illumination typically manifest as low-frequency or broad background. The window size of the large kernel median filter is much larger than the QR code module size, thus effectively filtering out high-frequency details and estimating the background image. Subtracting this background image from the original image preserves the target high-frequency signal while canceling out low-frequency background interference, enabling subsequent simple fixed-threshold binarization to achieve high-precision segmentation and ensuring high reliability and high fault tolerance in the decoding process.

[0020] 5. This invention first prints and cures a high-contrast base QR code to form a stable basic information layer. The coating and curing of a transparent isolation layer not only protects the base layer but, more importantly, provides a chemically inert and smooth interface, preventing ink from seeping between layers and ensuring pattern independence. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure in Embodiment 1 of the present invention.

[0022] Figure 2 This is the system identification logic diagram in Embodiment 2 of the present invention; Figure 3 This is a flowchart of the identification method in Embodiment 3 of the present invention; Figure 4 This is a flowchart of the preparation process in Example 4 of the present invention; The attached diagram shows the markings and corresponding component names: 101. Substrate; 102. First QR code layer; 103. Transparent isolation layer; 104. Second QR code layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0024] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly or indirectly attached to that other component. When a component is referred to as being "connected to" another component, it can be directly or indirectly connected to that other component.

[0025] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means an amphoteric material, such as white cardstock or PET film. Substrates may include one or more pre-defined auxiliary substrates, unless otherwise explicitly specified.

[0027] Example 1: A composite structure capable of recognizing two-layer QR codes, enabling the reading of two independent QR code information under different lighting conditions.

[0028] like Figure 1 As shown, the composite structure includes a substrate 101. The substrate 101, serving as the bottom layer supporting the entire functional structure, can be made of white cardstock. The substrate 101 itself should maintain optical stability in the subsequent preset auxiliary light band, and its surface properties should be conducive to ink adhesion and accurate printing of patterns.

[0029] A first QR code layer 102 is disposed on the surface of the substrate 101. This first QR code layer 102 is composed of two color regions with different reflective properties in a preset auxiliary light band. In this embodiment, the preset auxiliary light band is specifically selected as a center wavelength of 850 nanometers, allowing near-infrared light with a bandwidth of ±20 nanometers. The first color region of the first QR code layer 102 is white, and its reflectivity is referred to as the first reflectivity. This first color region is formed by screen printing with white ink containing titanium dioxide. The second color region is black, and its reflectivity is referred to as the second reflectivity. This second color region is formed by screen printing with black ink containing carbon black. To achieve clear imaging of the underlying QR code under auxiliary light, the ratio of the first reflectivity to the second reflectivity must be greater than 4:1. Measurements show that the reflectivity of the titanium dioxide white region at a wavelength of 850 nanometers exceeds 80%, while the reflectivity of the carbon black region is less than 10%. The ratio is greater than 8, satisfying the requirement of a ratio greater than 4, ensuring that the pattern of the first QR code layer 102 has extremely high optical contrast.

[0030] Above the first QR code layer 102, a transparent isolation layer 103 is applied and cured. This transparent isolation layer 103 is made of ultraviolet-cured varnish and completely seals the first QR code layer 102 inside. The main function of the transparent isolation layer 103 is to physically isolate the upper and lower QR code layers to prevent mutual interference, while providing a flat surface for further printing. In addition, the transparent isolation layer 103 has extremely high light transmittance in the preset 850 nm near-infrared light band, with a transmittance typically higher than 95%, ensuring that auxiliary light can pass through with almost no loss, reach the lower layer, and be reflected.

[0031] A second QR code layer 104 is disposed above the transparent isolation layer 103. This second QR code layer 104 consists of a white area and at least one third-color area forming the QR code pattern. In this embodiment, cyan is chosen as the third color. Under visible light such as natural light, the white and cyan areas exhibit significant differences in optical properties in the visible light band. For example, the white area reflects most visible light, while the cyan area absorbs some red and green light. This difference allows the pattern formed by the two areas to be clearly captured and recognized by standard visible light imaging devices such as mobile phone cameras. At this time, the observer or device can only perceive the information in the surface second QR code layer 104.

[0032] To achieve the goal of hiding surface information and revealing underlying information under a preset auxiliary light, the transmittance of both the white and cyan areas in the preset auxiliary light band must be greater than 70%, ensuring that near-infrared light of sufficient intensity can penetrate the second QR code layer 104 and reach the first QR code layer 102 below it.

[0033] Furthermore, the optical reflectivity of the white and cyan regions must be extremely close in this preset auxiliary light band. Assuming the ratio of the absolute difference in reflectivity between the white and cyan regions to their average reflectivity is less than 20%, under near-infrared light, the reflected light signal intensity from the white and cyan regions of the second QR code layer 104 itself is almost identical, causing the pattern of this layer to disappear in imaging, becoming a uniform background, thus preventing interference with the recognition of the underlying QR code.

[0034] To meet the aforementioned optical requirements, the ink of the second QR code layer 104 is specially designed. For the white areas, the ink contains hollow polymer microspheres as white pigment. These microspheres appear opaque white under visible light due to scattering, but the scattering effect is drastically reduced in the near-infrared band, thereby achieving high transmittance and low and controllable reflectance.

[0035] For the cyan areas, the ink contains phthalocyanine blue pigment to produce the cyan color, and must also contain a transparent nano-silica scattering agent. Phthalocyanine blue pigment has weak absorption in the near-infrared band, providing a basis for high transmittance. The transparent nano-silica scattering agent itself has almost no absorption in the near-infrared band, and its core function is to finely adjust the surface light scattering characteristics of the cyan ink film, thereby adjusting the near-infrared reflectance of the cyan area to a level that matches the reflectance of the white area, thus meeting the aforementioned requirement of low reflectance difference.

[0036] To verify the feasibility of the technical solution in this embodiment, corresponding samples were prepared and optical tests were conducted. At a wavelength of 850 nm, the transmittance of the white area was 75%, and the reflectance was 12.0%; the transmittance of the cyan area was 72%, and the reflectance was 11.5%. First, the transmittance of both the white and cyan areas is greater than 70%, meeting the high transmittance requirement. Second, the absolute value of the difference in reflectance between the two areas is |12.0%-11.5%|=0.5%; the average reflectance is (12.0%+11.5%) / 2=11.75%; the ratio is 0.5% / 11.75%≈4.26%. The calculated result of 4.26% is less than 20%, meeting the low reflectance difference requirement. This proves that the second QR code layer 104 has successfully achieved optical invisibility under near-infrared light.

[0037] In summary, under natural light, only the surface bluish-white second QR code layer 104 is visible and identifiable. When illuminated by a near-infrared light source with a center wavelength of 850 nm, the light efficiently penetrates the uniform second QR code layer 104 and is reflected by the high-contrast black and white first QR code layer 102. The imaging device will capture a clear pattern of the first QR code layer 102, thus achieving conditional reading and verification of dual information on a single carrier.

[0038] Example 2: A system capable of recognizing dual-layer QR codes. This system utilizes different lighting conditions to read information from a composite structure capable of recognizing dual-layer QR codes as described in Example 1, acquiring the information of two independent QR codes carried on its surface and bottom layers respectively. Figure 2 As shown, the system includes a composite structure capable of recognizing dual-layer QR codes as described in Example 1, a light source module, and an image acquisition and processing module.

[0039] The light source module emits light in a preset auxiliary wavelength band to excite and read the underlying information in the composite structure. In this embodiment, the preset auxiliary wavelength band is a near-infrared light band with a center wavelength of 850 nm and an allowable deviation of ±20 nm. Therefore, the light source module is configured to emit near-infrared light with a center wavelength of 850 nm. This can be achieved by an array of one or more high-power near-infrared light-emitting diodes, equipped with a light-diffusing device to ensure uniform illumination covering the surface of the composite structure to be identified. This specific wavelength band is chosen because the ink formulation of the second QR code layer 104 in the composite structure is designed to meet the optical conditions of transmittance greater than 70% and highly matched reflectance in this wavelength band, while the titanium dioxide and carbon black ink of the underlying first QR code layer 102 can produce a reflectance contrast ratio higher than 4:1 in this wavelength band.

[0040] The image acquisition and processing module is responsible for capturing images of the composite structure under near-infrared light illumination and resolving the pattern information of the first QR code layer 102 from it. This module is an image sensor sensitive to near-infrared light. In order for it to effectively sense near-infrared light with a wavelength of 850 nanometers, the image sensor must remove the infrared cut-off filter that is usually equipped in front of it to block infrared light, because the infrared cut-off filter in a standard camera blocks light near 850 nanometers, causing the sensor to be unable to receive effective reflected signals.

[0041] In front of the image sensor after removing the infrared cutoff filter, a narrowband filter precisely matched to the preset auxiliary light band needs to be installed. This narrowband filter also has a center transmission wavelength of 850 nm, and its bandwidth is typically ±10 to 20 nm. During imaging, the narrowband filter only allows near-infrared light with a center wavelength around 850 nm reflected back from the composite structure to pass through, while strongly attenuating or blocking visible light and stray light from other bands in the environment. This improves the signal-to-noise ratio and ensures that even under strong ambient light interference, the image sensor captures primarily effective signal images excited by the system's own near-infrared light source and reflected by the composite structure, thus guaranteeing the clarity and stability of the first QR code layer 102 pattern imaging.

[0042] In practical operation, under natural or indoor light conditions, the operator can easily scan and identify the clearly visible second QR code layer 104, composed of white and cyan, by using a common visible light camera (such as a mobile phone camera) aimed at the composite structure to obtain surface information. When it is necessary to read the hidden information at the bottom layer, the identification device is activated. The device's light source module emits uniform 850-nanometer near-infrared light, illuminating the composite structure. This light efficiently penetrates the optically uniform second QR code layer 104, reaching the high-contrast black and white first QR code layer 102 and being modulated and reflected by its pattern. The reflected light carrying the underlying information penetrates the second QR code layer 104 again, then passes through the 850-nanometer narrowband filter in front of the image acquisition and processing module, and is clearly captured by the image sensor with the infrared cutoff filter removed. Because the second QR code layer 104 reflects uniformly at 850 nanometers, it is almost invisible in the final image, while the high-contrast underlying black and white QR code pattern is clearly imaged. The processor in the image acquisition and processing module then performs grayscale conversion, binarization, positioning and decoding on the image, and finally accurately outputs the information carried by the first QR code layer 102. This invention realizes conditional switching reading of the double-layer QR code information in the composite structure.

[0043] Example 3: A method for recognizing composite structures of two-layer QR codes as described in Example 1. This method achieves sequential reading and reliable decoding of two independent QR code information layers on the same physical carrier by controlling the illumination conditions and image processing flow in stages. Figure 3 As shown.

[0044] This method involves image acquisition and decoding of a composite structure under visible light to obtain information about the second QR code layer 104 on its surface. This step can be performed directly using a device equipped with a standard visible light camera, such as a smartphone. During operation, the composite structure is placed under normal indoor or natural light to ensure that the pattern of the second QR code layer 104 on its surface is clearly visible. A color image containing white areas and a third color area (such as cyan) is acquired through the device's camera. This color image is then converted to grayscale and calculated using a weighted formula that conforms to human visual perception. Because the reflectivity of white and cyan areas differs significantly under visible light, the resulting grayscale image has high contrast. Therefore, the second QR code layer 104 can be decoded directly or after simple adaptive threshold binarization, using a standard QR code decoding library, successfully obtaining the first set of information carried by the surface layer.

[0045] Next, under a preset auxiliary light illumination environment, the same composite structure is image acquired again to obtain raw data for extracting underlying information. During operation, the light source module is activated and controlled to emit preset auxiliary light, which in this embodiment is near-infrared light with a center wavelength of 850 nanometers. Under the condition that the main ambient visible light is turned off or blocked, and only near-infrared light is used as the illumination source, the image acquisition and processing module is used to acquire images of the composite structure. Its image sensor has removed the infrared cutoff filter and installed an 850-nanometer narrowband filter. At this time, since the second QR code layer 104 has high transmittance and uniform reflectance in the 850-nanometer band, while the first QR code layer 102 has high contrast in this band, the raw image captured by the sensor mainly contains the target signal modulated by the bottom first QR code layer 102, but may still contain weak residual pattern signals and noise caused by the imperfect optical matching of the second QR code layer 104.

[0046] Therefore, background correction processing is performed on the original image acquired under the preset auxiliary light. The purpose is to suppress any weak signals that may remain in the second QR code layer 104 pattern, thereby further purifying the target image and improving the recognition robustness of the underlying QR code. An effective way to implement background correction processing is to subtract the background image obtained through large kernel median filtering from the original image. Specifically, let the acquired original near-infrared grayscale image be... The grayscale value of each pixel constitutes a mixture of the target signal and the background signal. Firstly, for... A background image is obtained by performing median filtering with a large kernel size. Median filtering is a non-linear filtering method. Its principle is to sort the grayscale values ​​of all pixels within a specified neighborhood of each pixel and take the median as the output for that point. When the selected filter kernel size is large enough, significantly larger than the size of a single black-and-white module in the bottom first QR code layer 102, this operation can effectively filter out small QR code module details while preserving broad, slowly changing background components in the image, including the low-frequency features of the residual pattern in the second QR code layer 104 that needs to be suppressed. Subsequently, a background correction operation is performed using the original image... Subtract background image To obtain the corrected image .

[0047] Then the image after background correction. Binarization is performed, and finally decoded to identify the first QR code layer 102. Since background correction has effectively suppressed interference, the corrected image mainly retains the high-contrast underlying QR code signal. At this point, a fixed threshold can be used for binarization segmentation, for example, pixels with a grayscale value greater than 100 are set to white (255), and pixels less than or equal to 100 are set to black (0). Binarization transforms the grayscale image into a pure black-and-white binary image, where white corresponds to the high-reflectivity part of the original underlying titanium dioxide region, and black corresponds to the low-reflectivity part of the original underlying carbon black region. Finally, by calling the QR code decoding algorithm on this clear black-and-white binary image, the second set of information carried by the first QR code layer 102 can be accurately and reliably identified.

[0048] In a practical test, after acquiring images of the sample from Example 1 under an 850 nm light source, a large kernel median filter was applied using a square window with a kernel size of 51 pixels by 51 pixels to obtain the background. After background correction, the signal-to-noise ratio in the image was significantly improved, and the underlying QR code pattern, which was almost indistinguishable to the naked eye, became clear and sharp. After binarization using a fixed threshold of 100, the decoding success rate increased from approximately 95% before background correction to over 99.5%, fully demonstrating the effectiveness and necessity of the background correction processing step in this recognition method for ensuring highly reliable reading of the underlying information.

[0049] Example 4: A method for preparing a composite structure capable of recognizing a double-layer QR code as described in Example 1.

[0050] like Figure 4As shown, firstly, a first QR code layer 102 is formed on a selected substrate 101. The substrate 101 is typically a smooth white cardboard. Using screen printing, a first color ink is used to print areas with high reflectivity in the first QR code layer 102 onto the surface of the substrate 101. In this embodiment, the first color is white, and the first color ink used is white ink containing titanium dioxide pigment. Next, a second color ink is used to screen print areas with low reflectivity in the first QR code layer 102 onto the same substrate 101. In this embodiment, the second color is black, and the second color ink used is black ink containing carbon black pigment. During printing, registration accuracy must be ensured, typically requiring a misalignment of less than 0.1 mm to guarantee the accuracy of the QR code pattern. After printing, the layer is dried in a hot air circulating oven at 80 degrees Celsius for 2 to 3 minutes to completely cure the ink, forming a robust first QR code layer 102 with high optical contrast. Under subsequent 850 nm near-infrared light, the reflectivity ratio of the titanium dioxide region to the carbon black region of this substrate will be greater than 8 to 1.

[0051] Next, a transparent optical adhesive layer is coated onto the cured first QR code layer 102. This transparent optical adhesive layer is typically a UV-curable varnish. The varnish is evenly applied to the entire surface of the first QR code layer 102 using a scraper or roller coating method, forming a wet film. The thickness of the wet film needs to be strictly controlled, typically between 15 and 20 micrometers, to ensure a uniform thickness of the transparent isolation layer 103 after curing. After coating, the substrate 101 is immediately placed under a UV curing device for irradiation and curing. The UV irradiation energy is controlled between 300 and 500 millijoules per square centimeter. Under the action of UV light, the photoinitiator in the varnish reacts, causing the liquid resin to rapidly crosslink and cure into a film, forming a hard, transparent, and smooth transparent isolation layer 103. The transmittance of this layer at a wavelength of 850 nanometers must be higher than 95% to ensure almost no attenuation of subsequent auxiliary light.

[0052] Then, a second QR code layer 104 is printed on the transparent isolation layer 103. This step also employs a high-precision screen printing process. First, a third-color area in the second QR code layer 104 is printed using a third-color ink. In this embodiment, the third color is cyan. The formulation of this third-color ink includes acrylic resin, phthalocyanine blue pigment, and a transparent nano-silica scattering agent. The phthalocyanine blue pigment provides the cyan color, while the transparent nano-silica scattering agent is used to finely control the surface scattering characteristics of the ink film in the near-infrared band. Next, a white area in the second QR code layer 104 is formed using white ink. The formulation of this white ink includes acrylic resin and hollow polymer microspheres as white pigment. The hollow polymer microspheres can produce strong scattering under visible light, thus appearing opaque white, while scattering weakens under near-infrared light, becoming transparent. During printing, the cyan area is printed first, followed by the white area, utilizing the stronger opacity of the white ink to ensure clear pattern edges. After printing, it is dried again at 80 degrees Celsius for 3 to 4 minutes to cure.

[0053] In the visible light band, both the white ink and the third color ink must have sufficient opacity to completely cover the pattern of the underlying first QR code layer 102. When printed on a black background with a film thickness of 10 to 15 micrometers, the contrast should be greater than 95% to ensure that the underlying pattern is completely invisible under natural light, with only the surface bluish-white pattern visible.

[0054] In the preset auxiliary light band, which in this embodiment is the near-infrared light band with a center wavelength of 850 nm and a bandwidth of ±20 nm, the white ink and the third color ink must meet the following requirements: the transmittance of both inks in this band must be greater than 70%; and the difference in optical reflectance between the two inks in this band must be less than 20% of their average reflectance.

[0055] Samples were prepared following the steps outlined above and the following example formulation: The white ink formulation is as follows: 45 parts by weight of acrylic resin, 12 parts by weight of hollow polymer microspheres with an average particle size of 0.3 micrometers, 3 parts by weight of fumed silica, 2 parts by weight of dispersant, and 38 parts by weight of ethyl acetate.

[0056] The cyan ink formula is as follows: 50 parts by weight of acrylic resin, 8 parts by weight of phthalocyanine blue 15:3 pigment, 5 parts by weight of transparent nano silica, 2 parts by weight of dispersant, and 35 parts by weight of ethyl acetate.

[0057] Spectral measurements were performed on the cured second QR code layer 104. The white area showed a transmittance of 75% and a reflectance of 12% at 850 nm; the cyan area showed a transmittance of 72% and a reflectance of 11.5% at 850 nm. The reflectance matching degree was calculated: the absolute value of the difference between the two was 0.5%, the average value was 11.75%, and the ratio was 4.3%, less than 20%, meeting the optical matching requirements. Simultaneously, all transmittance indicators also met the standards.

[0058] Working Principle: This invention designs a composite structure comprising a second QR code layer 104 with specific optical properties, a high-contrast first QR code layer 102, and a transparent isolation layer 103. The white and third color regions of the second QR code layer 104 have significant optical differences in the visible light band, forming a surface QR code that can be recognized by ordinary devices. Simultaneously, these two layers are configured in a preset auxiliary light band to have a transmittance greater than 70% and a reflectance difference less than 20% of their average value. This ensures that when illuminated by auxiliary light, the second QR code layer 104 becomes transparent due to its high transmittance and forms an optically uniform background due to its extremely low reflectance difference, thus no longer interfering with imaging. At this time, the pattern of the high-contrast first QR code layer 102 is clearly displayed and recognized. This invention fundamentally achieves a dual anti-counterfeiting and information hiding effect from a physical structure perspective: visible information under natural light and readable hidden information under auxiliary light. Furthermore, the two layers of information are completely independent and do not interfere with each other, resulting in high anti-counterfeiting strength.

[0059] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite structure capable of recognizing dual-layer QR codes, characterized in that, include: Substrate (101); The first QR code layer (102) is disposed on the surface of the substrate (101) and is formed by a first color region having a first reflectivity in a preset auxiliary light band and a second color region having a second reflectivity, wherein the ratio of the first reflectivity to the second reflectivity is greater than 4:

1. A transparent isolation layer (103) covers the first QR code layer (102); The second QR code layer (104) is disposed on the transparent isolation layer (103) and is formed by a white area and at least one third color area; The difference in optical properties between the white area and the third color area in the visible light band allows them to together form a QR code pattern that can be recognized by a standard visible light camera. Furthermore, the transmittance of both the white region and the third color region in the preset auxiliary light band is greater than 70%, and the difference in optical reflectance between the two in the preset auxiliary light band is less than 20% of their average reflectance.

2. The composite structure capable of recognizing dual-layer QR codes according to claim 1, characterized in that, The preset auxiliary light band is the near-infrared light band with a center wavelength of 850nm±20nm.

3. The composite structure capable of recognizing dual-layer QR codes according to claim 1, characterized in that, The first color area is formed by an ink containing titanium dioxide, and the second color area is formed by an ink containing carbon black.

4. The composite structure capable of recognizing dual-layer QR codes according to claim 1, characterized in that, The ink used in the white area contains hollow polymer microspheres as a white pigment.

5. The composite structure capable of recognizing dual-layer QR codes according to claim 1, characterized in that, The ink used in the third color region contains phthalocyanine blue pigment and transparent nano-silica scattering agent.

6. A system capable of recognizing dual-layer QR codes, characterized in that, include: A composite structure capable of recognizing dual-layer QR codes as described in any one of claims 1-5; The identification device includes a light source module for emitting the preset auxiliary light band, and an image acquisition and processing module for acquiring an image of the composite structure under the illumination of the preset auxiliary light band and identifying the first QR code layer (102).

7. A system for recognizing dual-layer QR codes according to claim 6, characterized in that, The image acquisition and processing module includes an image sensor with the infrared cutoff filter removed, and a narrowband filter located in front of the image sensor that matches the preset auxiliary light band.

8. A method for recognizing a composite structure capable of recognizing a double-layer QR code as described in any one of claims 1-5, characterized in that, Includes the following steps: In a visible light environment, an image of the composite structure is acquired, and the second QR code layer (104) is decoded; Images of the composite structure were acquired under a preset auxiliary light illumination environment; Background correction processing is performed on the image acquired under the preset auxiliary light to suppress residual signals of the second QR code layer (104) pattern; The image after background correction is binarized and decoded to identify the first QR code layer (102).

9. The identification method according to claim 8, characterized in that, The background correction process includes subtracting the background image obtained by large kernel median filtering from the original image.

10. A method for preparing a composite structure capable of recognizing a dual-layer QR code as described in any one of claims 1-5, characterized in that, Includes the following steps: The first QR code layer (102) is formed on the substrate (101) by screen printing using first color ink and second color ink; A transparent optical adhesive layer is coated on the first QR code layer (102), and after curing, the transparent isolation layer (103) is formed; On the transparent isolation layer (103), the second QR code layer (104) is formed by screen printing using white ink and third color ink; The white ink and the third color ink are configured to satisfy the following: in the visible light band, both have sufficient covering power to cover the underlying pattern; in the preset auxiliary light band, both have a transmittance greater than 70%, and the difference in optical reflectance is less than 20% of their average reflectance.

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