Optical effect layer

Abstract

The invention relates to a graphic element and is directed to an optical effect layer with stereoscopic depth-of-field vision. The problem of providing an optical effect anti-counterfeiting element is solved, and the optical effect layer is easy to identify by human eyes of binocular vision and does not need to be identified by special devices and equipment in an auxiliary manner; an optical effect layer anti-counterfeiting element with stereoscopic depth-of-field vision is generated through a first Moire image layer, a transparent optical refraction layer and a second Moire image layer which generates a Moire effect with the first Moire image layer, and the bottom layer principle is a visual light field regulation and control imaging technology based on the Moire effect. The moire imaging image is not required to obviously move along with different visual angles, only the three-dimensional depth-of-field visual effect is required, and only more open physical and mathematical conditions need to be followed in design, so that the design and manufacturing difficulty of the optical effect layer under the characteristic optical structure principle is further reduced, and the application range is increased.

Description

Technical Field

[0001] This invention relates to graphic elements and specifically to an optical effect layer with stereoscopic depth perception. More specifically, one application of this optical effect layer is in the field of security elements for protecting valuable documents and goods, as well as for brand protection. Alternatively, the optical effect layer can also be used for decorative purposes and in the field of display technology. Background Technology

[0002] Optical anti-counterfeiting technology possesses significant visual recognizability and is easily identifiable by the public, making it widely used in areas involving economic interests and public safety, such as branded products, important security documents, and securities. With continuous economic and technological development and increasingly fierce market competition, counterfeit and substandard products are proliferating. This poses a more severe challenge to printing and packaging companies and the anti-counterfeiting industry. Existing two-dimensional planar visual anti-counterfeiting technologies are insufficient to meet the anti-counterfeiting requirements and packaging aesthetics of high-end products, leading to the development of three-dimensional anti-counterfeiting technology. Three-dimensional anti-counterfeiting packaging technology offers advantages such as excellent anti-counterfeiting effects, simplicity and convenience, and high durability. Furthermore, it cannot be copied by ordinary photocopying or scanning methods, making it highly valuable for application.

[0003] 3D display anti-counterfeiting technologies mainly include three types: 3D printing anti-counterfeiting, lens array anti-counterfeiting, and laser 3D holographic anti-counterfeiting. Currently, the most widely used 3D printing anti-counterfeiting technology is grating-based 3D display anti-counterfeiting technology, which is mainly divided into lenticular grating and dot grating technologies. Dot grating and microlens array anti-counterfeiting technologies share the same principle, differing only in lens aperture size; their names are sometimes used interchangeably. Laser holographic anti-counterfeiting technology has been developed and applied for many years and is now common; some similar technical characteristics make it difficult for the public to effectively distinguish between genuine and counterfeit products.

[0004] Patent CN 120071747 A discloses a technique for achieving stereoscopic dynamic display using two correlated moiré image layers under the action of a transparent refractive layer, representing a new breakthrough in the field. While this technique is relatively easier to manufacture and lower in cost compared to previous methods, it remains difficult to apply to films smaller than 50 micrometers. It also faces numerous limitations in image design, failing to meet the design and processing requirements for ultra-thin materials, and still requires high image processing precision, thus posing challenges related to cost and efficiency. Summary of the Invention

[0005] This invention focuses solely on the requirements of stereoscopic display effects, further exploring the potential of moiré imaging-related technologies. Theoretically, it delves into visual light field manipulation techniques based on the moiré effect, overcoming the shortcomings of existing design techniques and some image processing techniques. It provides an optical effect layer element with stereoscopic depth-of-field vision that only needs to meet the design requirements of a more open moiré image layer. The technical solution adopted is as follows: An optical effect layer includes a first moiré image layer, a transparent optical refractive layer, and a second moiré image layer that generates a moiré effect with the first moiré image layer. The layer is characterized in that the absolute value of the difference between the moiré period *a* of the first moiré image layer and the moiré period *b* of the second moiré image layer at the corresponding overlapping position, along with the thickness *h* and refractive index *n* of the transparent refractive layer, satisfies the following condition: |ab|≦2h*tan(arcsin(1 / n)), and has one or more moiré magnification point images within the overlapping area of ​​the first and second moiré image layers. One characteristic structure consists of, in sequence, a first moiré image layer, a transparent optical refraction layer, and a second moiré image layer that generates a moiré effect with the first moiré image layer. This structure can produce a moiré magnified point image with a slight motion effect that exhibits stereoscopic depth of field depending on the viewing angle. Another characteristic structure consists of, in sequence, a first moiré image layer, a second moiré image layer that generates a moiré effect with the first moiré image layer, and a transparent optical refraction layer. When viewed from the transparent refraction layer side, this structure can produce a moiré magnified point image with a stereoscopic depth of field effect. A further characteristic structure consists of, in sequence, a first moiré image layer, a second moiré image layer that generates a moiré effect with the first moiré image layer, and a static planar reference image layer located within the first or second moiré image layer, without the transparent refraction layer. The key feature is that the overlapping area between the first and second moiré image layers contains one or more moiré magnified point images. This structure can also produce an overall image with a stereoscopic depth of field effect.

[0006] Inspired by existing research on microlens moiré imaging effects, another feasible structure for an optical effect layer is as follows: a reflective layer, a transparent refractive layer, a first moiré image layer, and a second moiré image layer that generates a moiré effect with the first moiré image layer. The absolute value of the difference between the moiré period 'a' of the first moiré image layer and the moiré period 'b' of the second moiré image layer at the corresponding overlapping position, along with the thickness 'h' and refractive index 'n' of the transparent refractive layer, satisfies the following condition: |ab|≦2h*tan(arcsin(1 / n)). Furthermore, there is one or more moiré magnification point images within the overlapping area of ​​the first and second moiré image layers. When viewed from the moiré image layer side, a moiré magnification point image with a stereoscopic depth-of-field visual effect can also be observed. Of course, a transparent protective layer can be added on this basis to form a structure consisting of a reflective layer, a transparent refractive layer, a first moiré image layer, a second moiré image layer that generates a moiré effect with the first moiré image layer, and a transparent protective layer.

[0007] Similarly, to prevent reverse engineering by making the design details of the moiré image difficult to observe under microscopy, a subtle transparent visual processing method is used for the first or second moiré image layer, such as printing transparent ink or frosted ink. Furthermore, the underlying principle of this invention can also be applied to the display field, its essence being the manipulation of light fields based on the moiré effect. Therefore, the first and second moiré image layers described in this invention are associated image layers that produce the moiré effect, and do not specifically refer to images with repetitive arrangement units in a general sense. Likewise, simple reprocessing based on the core technical principle of this invention should still fall within the scope of protection of this invention.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: This technical solution removes the restrictions on the size of the micro-units in the moiré image and also relaxes the restrictions on the period of the moiré image, making it easier to achieve the precision requirements of the optical effect layer with ultra-thin transparent refractive layer in image design and processing technology. However, for the sake of anti-counterfeiting and graphic processing technology, preferably, the size of the micro-units in the moiré image design is less than 500 micrometers, and the period of the moiré image is also less than 500 micrometers.

[0009] Similarly, preferably, since the depth of field effect is related to the moiré magnification and the thickness h of the transparent refractive layer, for ultra-thin transparent refractive layer materials, the design of the first and second moiré images with large moiré magnification can be appropriately considered. For easier identification of the depth of field effect, preferably, a static planar pattern can be designed in the first or second moiré image layer to enhance the visual contrast effect.

[0010] Similarly, this technical solution does not limit the type of moiré image. It can be a periodic moiré image, a variable periodic moiré image, or a random glass pattern moiré effect image. Preferably, the second moiré image is a periodic moiré image based on the first periodic moiré image and an encrypted moiré image based on the mathematical spatial transformation of the first periodic moiré image. This can better protect valuable documents and valuable goods. The mathematical spatial transformation algorithm present therein gives this optical effect layer better anti-counterfeiting performance.

[0011] Similarly, the transparent refractive layer of this technical solution can be achieved through additive manufacturing, such as printing a UV varnish layer, or it can be replaced by a transparent refractive substrate film layer, making the manufacturing methods and processes more diverse.

[0012] Similarly, this technical solution can adjust the final presentation effect by adjusting the positional relationship between the first moiré image layer, the transparent optical refractive layer, and the second moiré image layer that generates the moiré effect with the first moiré image layer, thereby achieving the goal of saving process costs in manufacturing. Attached Figure Description

[0013] Figure 1 shows the tiny unit of the array pattern.

[0014] Figure 2 shows the first moiré image layer of Example 1.

[0015] Figure 3 shows the second moiré image layer of Example 1.

[0016] Figure 4 To be according to Figure 2 and Figure 3 Visual effect image of the processed optical effect layer. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions in this application, the present invention will be described more fully below with reference to the accompanying drawings, and some embodiments of the present invention will be given. The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other implementations obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0018] technology Effective resolution (image detail capability) Minimum reproducible feature size Precision control (error range) offset printing 150–300 lpi (≈75–150 μm dot) ≥30 μm ±5–10 μm Flexographic printing 100–200 lpi (traditional) high-definition flexographic printing: 180–200 lpi Traditional: ≥50 μm; High-definition laser flexographic printing: ≥10 μm Traditional: ±15 μm; High-definition flexographic printing: ±5 μm Intaglio printing 200–400 lpi (≈25–50 μm) ≥20 μm ±3–5 μm silkscreen ≤80 lpi (≈150 μm) ≥100 μm ±20–50 μm Inkjet printing (industrial grade) 600–2400 dpi (effective ≈300–1200 dpi) ≥30–50 μm ±10–20 μm (affected by the printing substrate) Electrostatic imaging (HP Indigo et al.) 812–1200 dpi (effective ≈300–600 dpi) ≥40 μm ±8–15 μm Nanoimprint lithography (NIL) ≤100 nm (theoretical ≈254,000 dpi) 50–200 nm ±10 nm (template determined) Laser Direct Writing (LDW) 0.5–10 μm (≈2500–50,000 dpi) 0.5–5 μm ±0.1–0.5 μm As can be seen from the table above, the method for processing moiré images on a substrate according to the present invention includes common processing methods for small lines or graphics such as publishing and printing, micro-nano imprinting followed by color filling, moiré image diffraction rasterization imprinting, and laser direct writing. New optical characteristics can be formed according to various processing methods. For example, after moiré image diffraction rasterization imprinting, it has a color effect; subwavelength rasterization has a viewing angle color-changing effect close to a single color. Another example is that by using printing technology to print different single colors on different parts, after matching and contrasting colors, a viewing angle color-changing effect will also appear.

[0019] Because the image design elements of this invention are extremely small and related to the thickness and refractive index of the transparent refractive layer, according to the key parameter formula, the thinner the transparent refractive layer, the smaller the parameter value, which places more stringent requirements on the reproduction feature size achieved by moiré image design and processing. Taking a printed transparent varnish layer as the transparent refractive layer as an example, the thickness of the printed transparent varnish layer is usually between 20 and 80 micrometers. Taking 20 micrometers as an example, with a refractive index of 1.5, the key parameter 2h*tan(arcsin(1 / n)) = 35.78 micrometers. However, the actual image details are limited by the dot shape and ink diffusion, so the key parameter must be reduced further. As shown in the table above, according to the method in patent application CN 120071747 A, ultrathin transparent refractive layers can typically only be achieved through micro-nano imprinting and laser direct writing. This invention, by removing the limitations on the micro-unit size and period of the moiré image, only requires controlling the design position accuracy to be between a few micrometers and tens of micrometers. This makes it easier to achieve the precision requirements for image design and processing technology of optical effect layers with ultrathin transparent refractive layers, enabling processing methods such as offset printing and high-definition flexographic printing. The following section uses high-definition offset printing as an example to list some feasible manufacturing schemes.

[0020] The overall process involves determining the thickness and refractive index of the transparent refractive layer based on customer requirements, calculating key parameters, controlling the design drafts of the first and second moiré images using these key parameters, and finally publishing the confirmed design drafts for printing and processing.

[0021] Option 1: Print the first moiré image layer on a paper or plastic film substrate, apply a transparent varnish, and print the second moiré image on the varnish layer to obtain packaging material containing this optical effect layer.

[0022] Option 2: Print the first moiré image layer on a paper or plastic film substrate, print the second moiré image layer on a transparent film substrate, and then laminate the transparent film substrate with the substrate containing the first moiré image layer to obtain a packaging material containing this optical effect layer.

[0023] Option 3: Print the first moiré image layer on one side of the transparent film substrate, and print the second moiré image layer on the corresponding position on the other side of the transparent film substrate to obtain a packaging material containing this optical effect layer.

[0024] Option 4: Print the first moiré image layer and the second moiré image layer sequentially onto a paper or plastic film substrate, and then pass them through a transparent varnish layer to obtain packaging material containing this optical effect layer.

[0025] Option 5: Print the first moiré image layer on a paper or plastic film substrate, laminate a transparent film on it, and then print the second moiré image layer at the corresponding position on the transparent film layer to obtain a packaging material containing this optical effect layer.

[0026] Other graphic processing methods can be derived by referring to feasible solutions, such as changing the printed varnish layer to a localized UV varnish. Example

[0027] This embodiment uses a 0.02mm thick printed transparent varnish layer as a basis to detail the design of the striped moiré image and the fabrication method of this optical effect layer. Based on the 0.02mm thickness of the transparent varnish layer and a refractive index of 1.5, the key parameter 2h*tan(arcsin(1 / n)) = 35.78 micrometers is calculated, which is approximately 0.028 millimeters at the maximum optimal viewing angle of the human eye. This example employs a periodic array pattern design, where the tiny unit patterns of the array pattern are as follows... Figure 1 As shown, the dimensions are 0.12mm * 0.12mm. The horizontal period of the moiré array in the first moiré image is 0.214mm, and the vertical period is 0.3mm. Using coated paper or silver cardstock as the substrate ensures clear reproduction of the image in high-definition offset printing. In moiré imaging, the upper moiré array is called the revealing layer, and the lower moiré array is called the original layer. The layer containing the magnified moiré image formed by the original and revealing layers is called the imaging layer. The spatial transformation image of the original layer within the revealing layer is the imaging layer. In special designs, the arrangement of the original layers can be deduced by utilizing the regular movement effect of the imaging layer to obtain the specially designed original layer moiré image. In this case, the first moiré image is the revealing layer, and the second moiré image is the original layer. Because the thickness of the transparent refractive layer in this case is relatively small, a large moiré magnification is required. We take a magnification of 40x in both the horizontal and vertical directions (the imaging layer is 1mm away from the static image layer). Taking subsidence imaging as an example, the horizontal period of the moiré pattern array in the second moiré image is calculated to be 0.2088mm, and the vertical period is 0.2926mm. The absolute value of the difference between the moiré periods of the first and second moiré images is 0.0052mm in the horizontal direction and 0.0074mm in the vertical direction, both of which are less than the key parameter of 0.03578mm, therefore it is feasible. The design diagram of the first moiré image is shown below. Figure 2 As shown, the design drawing of the second Mohr image is as follows: Figure 3 As shown in the diagram. Based on the above calculations, it is evident that the design drawings for both the first and second moiré images are at the micrometer level, requiring spot color offset printing to ensure the positional accuracy of the moiré images in each layer. The registration accuracy between the first and second moiré image layers does not affect the overall imaging effect, only the imaging position, and is within an acceptable range. Taking a silver self-adhesive substrate as an example, the second moiré image layer, the first moiré image layer, and the transparent varnish layer are printed sequentially on the substrate layer using spot color printing. This yields packaging materials containing this optical effect layer, achieving the desired effect. Figure 4 As shown.

[0028] The above embodiments describe specific implementations of the present invention. However, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. An optical effect layer, comprising a first moiré image layer, a transparent optical refractive layer, and a second moiré image layer that generates a moiré effect with the first moiré image layer, characterized in that: The absolute value of the difference between the moiré period a of the first moiré image layer and the moiré period b of the second moiré image layer at the corresponding overlapping position, together with the thickness h and refractive index n of the transparent refractive layer, satisfies the following condition: |ab|≦2h*tan(arcsin(1 / n)), and there is one or more moiré magnification point images within the overlapping range of the first moiré image layer and the second moiré image layer.

2. The optical effect layer according to claim 1, wherein one of its characteristic structures is, in sequence, a first moiré image layer, a transparent optical refraction layer, and a second moiré image layer that generates a moiré effect with the first moiré image layer, wherein this structure can generate a moiré magnified point image with a slight motion of three-dimensional depth of field visual effect depending on the viewing angle.

3. The optical effect layer according to claim 1, wherein another characteristic structure comprises, in sequence, a first moiré image layer, a second moiré image layer that generates a moiré effect with the first moiré image layer, and a transparent optical refraction layer, wherein, when viewed from the transparent refraction layer side, this structure can produce a moiré magnified point image with a stereoscopic depth-of-field visual effect.

4. An optical effect layer, wherein a particular structure comprises, sequentially, a first moiré image layer, a second moiré image layer that generates a moiré effect with the first moiré image layer, and a static planar reference image layer located in the first or second moiré image layer, wherein a transparent refractive layer is removed, characterized in that: The first moiré image layer and the second moiré image layer overlap within a region containing one or more moiré magnification points. This structure can also produce an overall image with a stereoscopic depth-of-field visual effect.

5. An optical effect layer, comprising, in sequence, a reflective layer, a transparent refractive layer, a first moiré image layer, and a second moiré image layer that generates a moiré effect with the first moiré image layer, characterized in that: The absolute value of the difference between the moiré period a of the first moiré image layer and the moiré period b of the second moiré image layer at the corresponding overlapping position, together with the thickness h and refractive index n of the transparent refractive layer, satisfies the following condition: |ab|≦2h*tan(arcsin(1 / n)), and there is one or more moiré magnification point images within the overlapping range of the first moiré image layer and the second moiré image layer.

Images