Imaging film based on Fresnel lens micro image-text array structure

Abstract

The invention discloses an imaging film based on a Fresnel lens micro image-text array structure, and the film is characterized in that the film comprises a transparent film substrate; the composite structure micro-focusing element array layer is arranged on one surface of the transparent film substrate and comprises a plurality of composite structure micro-focusing element units, and each composite structure micro-focusing element unit is obtained by performing Fresnel lens on a micro image-text array, so that a Fresnel lens micro image-text array structure is formed; an ultraviolet adhesive layer is arranged between the adjacent composite structure micro focusing element units, and the ultraviolet adhesive layer is higher than the Fresnel lens micro image-text array structure; and the reflecting film layer covers the surface of the Fresnel lens micro image-text array structure. The imaging thin film is large in visual angle and thin in thickness, the Fresnel micro lens array and the micro image-text array form a composite structure, the technological process is optimized, the production cost is reduced, and a thin film type imaging device with ultra-thin and flexible characteristics can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of optical anti-counterfeiting, and in particular to an imaging film based on a Fresnel lens micro-image array structure. Background Art

[0002] In recent years, counterfeit and shoddy goods have flooded the major markets in my country, such as various famous brand wines, cigarettes, food, beverages, medicines, health products, cosmetics, detergents, clothing, footwear, film, medical equipment, steel, cement, chemical raw materials, fertilizers, pesticides, seeds, auto parts, televisions, etc.; and in the field of social public security, there are also a large number of counterfeit banknotes, stamps, various securities, resident identity cards, household registers, graduation certificates, qualification certificates, official seals, etc. The variety of counterfeit and shoddy goods involved, the wide distribution range, and the serious consequences caused are really shocking. In particular, counterfeit banknotes and various identity and qualification certificates are the most harmful to society. Therefore, in order to prevent goods from being counterfeited, it is particularly important to use scientific and technological means to protect high-quality brand-name goods and eliminate counterfeit and shoddy goods.

[0003] Common public anti-counterfeiting technologies mainly include printing, watermarking, laser holography and color-changing inks. Printing and watermarking are easy to copy and forge through digital photography, scanning, copying, etc. In recent years, people have developed many different types of color-changing inks, such as temperature-changing, light-changing and fluorescent types. Color-changing inks must be combined with other technologies to achieve anti-counterfeiting functions. Laser holographic technology has attracted widespread attention based on the principle of holographic imaging and colorful flashes, dynamics and three-dimensional effects. It was once recognized as the most advanced and cost-effective technology. However, with the widespread application of holography in the fields of tickets, trademarks, packaging, etc., many manufacturers have the ability to produce holographic products, which has put laser holographic anti-counterfeiting technology into crisis. Therefore, people are in urgent need of finding a new generation of public anti-counterfeiting technology that meets the requirements of high technology, low cost and easy identification.

[0004] Chinese invention patent CN103236222B discloses an anti-counterfeiting security film based on the principle of integrated imaging and having a dynamic three-dimensional effect, including a microlens array layer and a unit image array layer. The unit image array layer includes a plurality of unit images storing image information of target scenes at different viewing angles. The microlens array layer includes microlenses arranged in one-to-one correspondence with the unit images and used to image the unit images. However, the patent is based on a transparent medium layer, with a microlens array and a micro-image array on both sides, that is, a two-layer structure, which makes the process complicated and the cost high. Summary of the invention

[0005] In order to solve the defects of the prior art, the present invention proposes an imaging film based on a Fresnel lens micro-image array structure.

[0006] The imaging film based on the Fresnel lens micro-image array structure of the present invention comprises: a transparent film substrate; a composite structure micro-focusing element array layer, which is arranged on a surface of the transparent film substrate and comprises a plurality of composite structure micro-focusing element units, each composite structure micro-focusing element unit is obtained by subjecting a micro-image array to Fresnel lensing, thereby forming a Fresnel lens micro-image array structure, and an ultraviolet adhesive layer is provided between adjacent composite structure micro-focusing element units, wherein the ultraviolet adhesive layer is higher than the Fresnel lens micro-image array structure; and a reflective film layer, which covers the surface of the Fresnel lens micro-image array structure.

[0007] Preferably, there is no optical interface between the transparent film substrate and the composite structure micro-focusing element array layer.

[0008] Preferably, the plurality of composite structure micro-focusing element units are arranged in a honeycomb array, a periodic regular arrangement, or an irregular non-periodic random arrangement.

[0009] Preferably, the period of the composite structure micro-focusing element array layer is 0.1 mm, and the structure depth is less than 10 microns.

[0010] Preferably, the micro-image array includes a plurality of micro-image units, each of which is an image to be presented.

[0011] Preferably, the micro-graphic units include micro-graphic strokes and / or images in a dense or sparse honeycomb arrangement, a periodic regular arrangement such as a square arrangement, or an irregular non-periodic random arrangement, thereby forming a micro-graphic array.

[0012] Preferably, the composite structure micro-focusing element array layer is obtained by the following method:

[0013] After the micro-image array and the Fresnel micro-lens array are aligned, the corresponding Fresnel micro-lens array structure is manufactured only in the micro-image array area by using photolithography technology, that is, the micro-image array is Fresnel-lensed, while other areas retain a higher ultraviolet adhesive layer than the composite structure micro-focusing element array, so that the Fresnel lensed micro-image array structure is presented in the pits of the ultraviolet adhesive layer.

[0014] Preferably, the actual imaging distance is within the range of ±20% of the optimal imaging distance by controlling the structural thickness of the composite structure micro-focusing element array layer and the curvature radius of the structural surface.

[0015] Preferably, the reflective film layer is an aluminum film.

[0016] Preferably, the reflective film layer has a thickness of 20 nm to 100 nm.

[0017] The beneficial effects of the present invention are:

[0018] 1. The imaging film of the present invention has a large viewing angle and a thin thickness. The Fresnel microlens array and the micro-image array form a composite structure, which optimizes the process flow, reduces the production cost, and can realize a film-type imaging device with ultra-thin and flexible characteristics.

[0019] 2. The imaging film of the present invention, through the combined action of the composite structure micro-focusing element array layer and the reflective film layer, the micro-image array composed of Fresnel lenses reflects the incident light, thus providing a high-contrast, bright stereoscopic image.

[0020] 3. Each composite structure micro-focusing element in the present invention logically processes the Fresnel micro-lens array and the micro-graphic array, and the graphic structure is hidden in the Fresnel array structure, which is extremely difficult to manufacture and cannot be imitated.

[0021] 4. The present invention has only one layer of composite structure micro-focusing element array layer on the transparent film substrate, and there is no need to consider interface reflection, and the imaging clarity is high.

[0022] 5. The present invention has a wide range of applications and has application value in the fields of visual anti-counterfeiting, for example, it can be used for product logos, labels or billboards. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the implementation methods in combination with the following drawings, among which:

[0024] Figure 1 Schematic diagram of an imaging film based on a Fresnel lens micro-image array structure according to a preferred embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of a virtual three-dimensional moiré image established by taking the Bagua Tai Chi diagram as an example in a preferred embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the imaging principle of a micro-image array structure based on Fresnel lensing according to a preferred embodiment of the present invention.

[0027] Figure 4 It is a schematic diagram of the unit structure in a partial area of ​​a Fresnel lens-based micro-image array according to a preferred embodiment of the present invention.

[0028] Figure 5 The present invention is a flow chart of a method for preparing an imaging film based on a Fresnel lens micro-image array structure according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Figure 1 Schematic diagram of an imaging film based on a Fresnel lens micro-image array structure according to a preferred embodiment of the present invention. Figure 1 As shown, the imaging film of the present invention comprises: a transparent film substrate 24; a composite structure micro-focusing element array layer, which is arranged on a surface of the transparent film substrate 24, and includes a plurality of composite structure micro-focusing element units, each composite structure micro-focusing element unit is obtained by Fresnel lensing a micro-image array, thereby forming a Fresnel lensed micro-image array structure 21, and there is an ultraviolet adhesive layer 23 between adjacent composite structure micro-focusing element units, and the ultraviolet adhesive layer 23 is higher than the Fresnel lensed micro-image array structure 21; and a reflective film layer 22, which covers the surface of the Fresnel lensed micro-image array structure. Preferably, the transparent film substrate 11 can be a PET material. The ultraviolet adhesive layer 23 can be a UV adhesive layer.

[0031] In each preferred embodiment, the aperture of each unit of the composite structure micro-focusing element array layer is 25 to 250 microns. The arrangement of each unit is a periodic regular arrangement such as a dense or sparse honeycomb arrangement, a square arrangement, or an irregular non-periodic random arrangement. The period of the composite structure micro-focusing element array layer is 0.05 mm to 0.6 mm, and the structural depth is less than 10 microns.

[0032] In each preferred embodiment, the micro-image array includes a plurality of micro-image units, each of which is an image to be presented. The micro-image units include micro-image strokes and / or images, which are arranged in a dense or sparse honeycomb arrangement, a periodic regular arrangement such as a square arrangement, or an irregular non-periodic random arrangement, thereby forming a micro-image array. Figure 2The present invention is a schematic diagram of a moiré image established by taking the Bagua Taiji diagram as an example in a preferred embodiment of the present invention. If the image to be presented is the Bagua Taiji diagram, the micro-image unit is the Bagua Taiji diagram. The image is a virtual three-dimensional object image suitable for a Fresnel lensed micro-image array structure in a UV adhesive pit. Through the imaging film of the present invention, a three-dimensional image can be observed in which the Taiji diagram floats relative to the film surface and the Bagua diagram sinks relative to the film surface. The microstructures of the Taiji diagram and the Bagua diagram are designed according to the moiré imaging principle, respectively, to form the visual effects of floating and sinking, respectively.

[0033] In each preferred embodiment, the composite structure micro-focusing element array layer is obtained by:

[0034] After the micro-image array and the Fresnel micro-lens array are aligned, the corresponding Fresnel micro-lens array structure 21 is manufactured only in the micro-image array area (within the image area) by using photolithography technology, that is, the micro-image array is Fresnel-lensed, while the other areas retain the ultraviolet adhesive layer 23 that is higher than the composite structure micro-focusing element array, so that the Fresnel lensed micro-image array structure 21 in the pit of the ultraviolet adhesive layer 23 is presented.

[0035] In each preferred embodiment, by controlling the structural thickness of the composite structure micro-focusing element array layer and the curvature radius of the structural surface, the actual imaging distance is within the range of ±20% of the optimal imaging distance. Preferably, the structural thickness is 25 microns to 250 microns, and the curvature radius of the surface is 12.5 microns to 125 microns. In this way, the bevel width in the Fresnel lens can adapt to the grayscale lithography resolution and have a better imaging effect.

[0036] In each preferred embodiment, the reflective film layer 13 is composed of an optical film with a reflective effect, such as a metal material, including aluminum, nickel, silver and chromium, and alloys thereof. Preferably, the thickness of the reflective film layer 13 is 20nm to 200nm. In other preferred embodiments, the reflective film layer 13 can also be composed of a multilayer film system of non-metallic materials, such as zinc oxide, silicon dioxide, magnesium fluoride and titanium dioxide.

[0037] In each preferred embodiment, there is no optical interface between the transparent film substrate 11 and the composite structure micro-focusing element array layer, that is, no reflection occurs when light passes through one layer into the other layer.

[0038] In each preferred embodiment, the depth (thickness) of the imaging film of the present invention is between 1 micron and 10 microns.

[0039] Through the present invention Figure 1 With the imaging film structure shown, people can observe bright stereoscopic images with naked eyes. Figure 3This is a schematic diagram of the imaging principle of the Fresnel lens micro-image array structure according to the preferred embodiment of the present invention. Since the UV adhesive layer 23 and the transparent film substrate 24 (PET substrate) are light-transmissive, the background outside the micro-image structure seen by the human eye is transparent. When the light is incident on the reflective film on the surface of the Fresnel lens structure, it is reflected and enters the human eye. Since the micro-image array part is still designed according to the principle of moiré imaging, the reflected light presents a bright image that can be seen by the human eye.

[0040] Figure 4 FIG. 1 is a schematic diagram of a unit structure in a partial area of ​​a Fresnel lens micro-image array according to a preferred embodiment of the present invention. Figure 4 As shown, the unit structures (Fresnel lens micro-image units) are regularly arranged in a honeycomb shape, and the width of each unit structure is 40 microns. Figure 4 It is shown in FIG. 1 that in each unit, the image and text area is the Fresnel lens area, and the white part is the area without image and text, which is the UV adhesive layer.

[0041] Figure 5 The flowchart of the method for preparing an imaging film based on a Fresnel lens micro-image array structure according to a preferred embodiment of the present invention is shown in FIG. The method comprises the following steps:

[0042] Step a: coating photoresist 142 on substrate (transparent film base) 141.

[0043] Step b, using grayscale maskless photolithography to make a composite micro-focusing element array layer 143. In this step, after aligning the micro-image array with the Fresnel micro-lens array, only the micro-image array area (within the image area) is aligning with the corresponding Fresnel micro-lens array structure using photolithography, that is, the micro-image array is Fresnel lensed, while other areas retain a higher photoresist layer than the composite structure micro-focusing element array, so that the Fresnel lensed micro-image array layer in the photoresist layer pits is presented. Specifically, according to the grayscale map of the structure design of the imaging film of the present invention, the composite micro-focusing element array structure is formed at one time using photolithography based on the grayscale map.

[0044] Step c: using ultraviolet nanoimprinting technology to transfer the composite micro-focusing element array mold 147.

[0045] Step d: Use the mold prepared in step S3 to continue replicating the composite micro-focusing element array of UV adhesive material.

[0046] Step e: coating the surface of the structure formed in step S4 with a reflective film layer 146. Preferably, the reflective film is an aluminum film.

[0047] Step f, using a method similar to ink scraping, a protective liquid 144 is scraped into the groove of the UV adhesive layer on the surface of the sample to cover the graphic structure part in the groove.

[0048] Step g, washing the surface of the sample with sodium hydroxide solution 145, so that the aluminum film on the surface of the UV adhesive layer is washed away, while the aluminum film on the surface of the micro-image array structure is not in contact with the sodium hydroxide solution due to the coverage of the protective liquid, so this part of the aluminum film reflective layer is retained.

[0049] Step h: forming an aluminum film reflective layer 146 only on the surface of the Fresnel lensed micro-image array structure by the above-mentioned zero-to-zero aluminum washing method, thereby manufacturing the imaging film based on the Fresnel lensed micro-image array structure of the present invention.

[0050] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. An imaging film based on a Fresnel lens micro-image array structure, characterized in that: include: Transparent film substrate; A composite structure micro-focusing element array layer is arranged on one surface of the transparent film substrate, and includes a plurality of composite structure micro-focusing element units, each composite structure micro-focusing element unit is obtained by performing Fresnel lensing on a micro-image array, thereby forming a Fresnel lensed micro-image array structure, and a photoresist layer is provided between adjacent composite structure micro-focusing element units, and the photoresist layer is higher than the Fresnel lensed micro-image array structure; as well as, A reflective film layer covers the surface of the Fresnel lens micro-image array structure.

2. The imaging film based on the Fresnel lens micro-image array structure according to claim 1, characterized in that: There is no optical interface between the transparent film substrate and the composite structure micro-focusing element array layer.

3. The imaging film based on the Fresnel lens micro-image array structure according to claim 2, characterized in that: The plurality of composite structure micro-focusing element units are arranged in a honeycomb array, a periodic regular arrangement, or an irregular non-periodic random arrangement.

4. The imaging film based on the Fresnel lens micro-image array structure according to claim 3, characterized in that: The period of the composite structure micro-focusing element array layer is 0.1 mm, and the structure depth is less than 10 microns.

5. The imaging film based on the Fresnel lens micro-image array structure according to claim 1, characterized in that: The micro-image array includes a plurality of micro-image units, each of which is an image to be presented.

6. The imaging film based on the Fresnel lens micro-image array structure according to claim 5, characterized in that: The micro-graphic units include micro-graphic strokes and / or images in a compact or sparse honeycomb arrangement, a periodic regular arrangement such as a square arrangement, or an irregular non-periodic random arrangement, thereby forming a micro-graphic array.

7. The imaging film based on the Fresnel lens micro-image array structure according to claim 6, characterized in that: The composite structure micro-focusing element array layer is obtained by the following method: After the micro-image array and the Fresnel micro-lens array are aligned, the corresponding Fresnel micro-lens array structure is manufactured only in the micro-image array area by using photolithography technology, that is, the micro-image array is Fresnel-lensed, while other areas retain a higher ultraviolet adhesive layer than the composite structure micro-focusing element array, so that the Fresnel lensed micro-image array structure is presented in the pits of the ultraviolet adhesive layer.

8. The imaging film based on the Fresnel lens micro-image array structure according to claim 1, characterized in that: By controlling the structural thickness of the composite structure micro-focusing element array layer and the curvature radius of the structural surface, the actual imaging distance is within the range of ±20% of the optimal imaging distance.

9. The imaging film based on the Fresnel lens micro-image array structure according to claim 1, characterized in that: The reflective film layer is an aluminum film.

10. The imaging film based on the Fresnel lens micro-image array structure according to claim 9, characterized in that: The thickness of the reflective film layer is 20nm to 100nm.

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