Imaging film based on Fresnel lens-shaped micro-graphic array structure

Abstract

The present invention discloses an imaging film based on a Fresnel lens-shaped micro-graphic array structure, which is characterized in that it includes: a transparent film substrate; a composite structure micro-focusing element array layer disposed on one surface of the transparent film substrate, including a plurality of composite structure micro-focusing element units, each composite structure micro-focusing element unit is obtained by performing Fresnel lens shaping on a micro-graphic array, so as to form a Fresnel lens-shaped micro-graphic array structure, and there is an ultraviolet glue layer between adjacent composite structure micro-focusing element units, and the ultraviolet glue layer is higher than the Fresnel lens-shaped micro-graphic array structure; and a reflective film layer covering the surface of the Fresnel lens-shaped micro-graphic array structure. The imaging film in the present invention has a large viewing angle and a thin thickness. The Fresnel microlens array and the micro-graphic array form a composite structure, which optimizes the process flow and reduces the production cost, and can realize a thin-film type imaging device with ultra-thin flexible characteristics.

Description

Technical Field

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

[0002] In recent years, counterfeit and shoddy goods have flooded the major markets in our country, such as various famous-brand wines, cigarettes, foods, beverages, medicines, health products, cosmetics, washing products, clothing, shoes, films, medical devices, steel, cement, chemical raw materials, fertilizers, pesticides, seeds, auto parts, televisions, etc.; in terms of the field of social public security, there are also a large number of forged banknotes, stamps, various negotiable securities, resident identity cards, household registers, graduation certificates, qualification certificates, official seals, etc. The types of counterfeit and shoddy goods involved are numerous, the distribution range is wide, and the consequences are extremely serious, which is really shocking. In particular, forged banknotes and various identity and qualification certificates pose the most serious harm 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 famous-brand goods and eliminate counterfeit and shoddy goods.

[0003] Common public anti-counterfeiting technologies mainly include printing, watermarking, laser holography, and color-changing inks, etc. Printing and watermarking are easily replicated and forged through digital photography, scanning, photocopying, etc. In recent years, various types of color-changing inks have been developed, such as temperature-variable type, light-variable type, and fluorescent type, etc. Color-changing inks must be combined with other technologies to achieve the anti-counterfeiting function. Laser holography technology has attracted widespread attention due to its holographic imaging principle and colorful flash, dynamic, and three-dimensional effects. It was once recognized as the most advanced and cost-effective technology. However, with the wide application of holography in the fields of tickets, trademarks, packaging, etc., many manufacturers already have the ability to produce holographic products, which has put the laser holographic anti-counterfeiting technology in crisis. Therefore, people are urgently in need of finding a new generation of public anti-counterfeiting technology that meets high technology, low cost, and easy recognition.

[0004] Chinese invention patent CN103236222B discloses an anti-counterfeiting security film based on the principle of integral 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 different perspectives of a target scene. The microlens array layer includes microlenses corresponding to the unit images one by one and used for imaging the unit images. However, this patent is based on a transparent medium layer, with a microlens array and a micro-graphic array on both sides respectively, that is, a two-layer structure, which makes the process flow complex and the cost relatively high. Summary of the Invention

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

[0006] An imaging film based on a Fresnel-lensified micro-graphic array structure according to the present invention includes: a transparent film substrate; a composite structure micro-focusing element array layer disposed on one surface of the transparent film substrate, including a plurality of composite structure micro-focusing element units, each composite structure micro-focusing element unit being obtained by Fresnel-lensifying a micro-graphic array, thereby forming a Fresnel-lensified micro-graphic array structure, and there being an ultraviolet glue layer between adjacent composite structure micro-focusing element units, the ultraviolet glue layer being higher than the Fresnel-lensified micro-graphic array structure; and a reflective film layer covering the surface of the Fresnel-lensified micro-graphic 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 arrangement, a periodic regular arrangement, or an irregular aperiodic 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-graphic array includes a plurality of micro-graphic units, and each micro-graphic unit is an image to be presented.

[0011] Preferably, the micro-graphic unit includes micro-graphic strokes and / or images, and is arranged in a honeycomb arrangement, a square arrangement, or other periodic regular arrangements that are compact or sparse, or an irregular aperiodic 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 aligning the micro-graphic array with the Fresnel microlens array, only the corresponding Fresnel microlens array structure is fabricated in the micro-graphic array region by photolithography technology, that is, the micro-graphic array is Fresnel-lensified, and a higher ultraviolet glue layer than the composite structure micro-focusing element array is retained in other regions, so that the Fresnel-lensified micro-graphic array structure in the pits of the ultraviolet glue layer is presented.

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

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

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

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

[0018] 1. The imaging film in the present invention has a large viewing angle and a thin thickness. The Fresnel microlens array and the micro-graphic array form a composite structure, optimizing the process flow and reducing the production cost, and can realize a film-type imaging device with ultra-thin 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, reflects the incident light by the micro-graphic array composed of Fresnel lenses, thus providing a stereoscopic image with high contrast and bright effect.

[0020] 3. Each composite structure micro-focusing element in the present invention performs logical processing on the Fresnel microlens array and the micro-graphic array, and the graphic structure is hidden in the Fresnel array structure, which has the characteristics of extremely high manufacturing difficulty and being impossible to imitate.

[0021] 4. The present invention has only one composite structure micro-focusing element array layer on the transparent film substrate, without considering interface reflection, and has high imaging clarity.

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

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings. The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

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

[0025] Figure 2 Schematic diagram of a virtual three-dimensional Moiré image established with the Bagua Taiji diagram as an example according to a preferred embodiment of the present invention.

[0026] Figure 3 Schematic diagram of the imaging principle based on a Fresnel lens-formed micro-graphic array structure according to a preferred embodiment of the present invention.

[0027] Figure 4 Schematic diagram of the unit structure in a partial area based on a Fresnel lens-formed micro-graphic array according to a preferred embodiment of the present invention.

[0028] Figure 5 Flow chart of the preparation method of the imaging film based on the Fresnel lens-shaped micro-graphic array structure, which is a preferred embodiment of the present invention. Specific embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] Figure 1 Schematic diagram of the imaging film based on the Fresnel lens-shaped micro-graphic array structure, which is a preferred embodiment of the present invention. As Figure 1 shown, the imaging film of the present invention includes: a transparent film substrate 24; a composite structure micro-focusing element array layer disposed on one surface of the transparent film substrate 24, including a plurality of composite structure micro-focusing element units, each composite structure micro-focusing element unit is obtained by performing Fresnel lens transformation on the micro-graphic array, so as to form a Fresnel lens-shaped micro-graphic array structure 21, and there is an ultraviolet glue layer 23 between adjacent composite structure micro-focusing element units, and the ultraviolet glue layer 23 is higher than the Fresnel lens-shaped micro-graphic array structure 21; and a reflective film layer 22 covering the surface of the Fresnel lens-shaped micro-graphic array structure. Preferably, the transparent film substrate 11 can be made of PET material. The ultraviolet glue layer 23 can be a UV glue layer.

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

[0032] In each preferred embodiment, the micro-graphic array includes a plurality of micro-graphic units, and each micro-graphic unit is an image to be presented. The micro-graphic unit includes micro-graphic strokes and / or images, and is arranged in a periodic regular arrangement mode such as a compact or sparse honeycomb arrangement, a square arrangement, etc., or an irregular aperiodic random arrangement mode, so as to form a micro-graphic array. Figure 2Schematic diagram of a Moiré image established with the Bagua Taiji diagram as an example for the preferred embodiment of the present invention. If the image to be presented is the Bagua Taiji diagram, the micro-graphic unit is the Bagua Taiji diagram. This image is a virtual three-dimensional object image suitable for a Fresnel lens-formed micro-graphic array structure in the pits of the ultraviolet glue. Through the imaging film of the present invention, a three-dimensional image in which the Taiji diagram floats relative to the film surface and the Bagua diagram sinks relative to the film surface can be observed. The micro-structures 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 the following method:

[0034] After aligning the micro-graphic array with the Fresnel microlens array, only the corresponding Fresnel microlens array structure 21 is fabricated in the area of the micro-graphic array (within the graphic area) by lithography technology, that is, the micro-graphic array is Fresnel lens-formed, while the ultraviolet glue layer 23 higher than the composite structure micro-focusing element array is retained in other areas, so that the Fresnel lens-formed micro-graphic array structure 21 in the pits of the ultraviolet glue 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 radius of curvature of the structure surface, the actual imaging image distance is within the range of ±20% of the optimal imaging image distance. Preferably, the structural thickness is 25 microns to 250 microns, and the radius of curvature of the surface is 12.5 microns to 125 microns. This enables the width of the inclined teeth in the Fresnel lens to adapt to the gray-scale lithography resolution and has a good imaging effect.

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

[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 enters one layer from 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 The imaging film structure shown enables people to observe a bright three-dimensional image with the naked eye. Figure 3Schematic diagram of the imaging principle of the Fresnel lens-based micro-graphic array structure according to the preferred embodiment of the present invention. Since the ultraviolet glue layer 23 and the transparent film substrate 24 (PET substrate) are light-transmissive, the background outside the micro-graphic structure seen by the human eye is transparent. When light is incident on the reflective film on the surface of the Fresnel lens structure, it is reflected into the human eye. And since the micro-graphic array part is still designed according to the principle of Moiré imaging, the reflected light presents a bright image visible to the human eye.

[0040] Figure 4 Schematic diagram of the unit structure in a partial area of the Fresnel lens-based micro-graphic array according to the preferred embodiment of the present invention. As Figure 4 shown, the unit structures (Fresnel lens-based micro-graphic units) are regularly arranged in a honeycomb pattern. The width of each unit structure is 40 microns. Figure 4 It shows that within each unit, the graphic area is the Fresnel lens area, and the white part is the area without graphics, which is the ultraviolet glue layer.

[0041] Figure 5 Flowchart of the preparation method of the imaging film based on the Fresnel lens-based micro-graphic array structure according to the preferred embodiment of the present invention. The preparation method includes the following steps:

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

[0043] Step b, fabricating a composite micro-focusing element array layer 143 using gray-scale maskless lithography technology. In this step, after aligning the micro-graphic array with the Fresnel microlens array, only the corresponding Fresnel microlens array structure is fabricated using lithography technology in the micro-graphic array area (within the graphic area), that is, the micro-graphic array is Fresnel lensified, while the photoresist layer in other areas is retained higher than the composite structure micro-focusing element array, so that the Fresnel lensified micro-graphic array layer in the pits of the photoresist layer is presented. Specifically, a gray-scale image is designed according to the structure of the imaging film of the present invention, and the composite micro-focusing element array structure is formed in one step using lithography technology based on this gray-scale image.

[0044] Step c, transferring the composite micro-focusing element array mold 147 using ultraviolet nanoimprinting technology.

[0045] Step d, continuing to replicate the composite micro-focusing element array of the UV glue material using the mold prepared in step S3.

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

[0047] Step f: On the surface of the sample, in a way similar to ink scraping, scrape a protective liquid 144 into the grooves of the UV glue layer to cover the graphic structure part in the grooves.

[0048] Step g: Rinse the surface of the sample with a sodium hydroxide solution 145 so that the aluminum film on the surface of the UV glue layer is rinsed off. Since the aluminum film on the surface of the micro-graphic array structure is covered by the protective liquid and does not come into contact with the sodium hydroxide solution, this part of the aluminum film reflective layer is retained.

[0049] Step h: Through the above zero-to-zero aluminum washing method, form an aluminum film reflective layer 146 only on the surface of the Fresnel lens-shaped micro-graphic array structure, thereby manufacturing the imaging film of the present invention based on the Fresnel lens-shaped micro-graphic array structure.

[0050] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An imaging film based on a Fresnel lens-shaped micro-graphic array structure, characterized in that, Comprising: A transparent thin film substrate; A composite structure micro-focusing element array layer disposed on one surface of the transparent thin film substrate, including a plurality of composite structure micro-focusing element units. Each composite structure micro-focusing element unit is obtained by performing Fresnel lensification on a micro-graphic array, thereby forming a Fresnel lensified micro-graphic array structure. There is a photoresist layer between adjacent composite structure micro-focusing element units, and the photoresist layer is higher than the Fresnel lensified micro-graphic array structure; And, A reflective film layer covering the surface of the Fresnel lensified micro-graphic array structure.

2. The imaging film based on the Fresnel lensified micro-graphic array structure according to claim 1, wherein, There is no optical interface between the transparent thin film substrate and the composite structure micro-focusing element array layer.

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

4. The imaging film based on the Fresnel lensified micro-graphic 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 thin film based on the Fresnel lens-formed micro-graphic array structure according to claim 1, characterized in that, The micro-graphic array includes a plurality of micro-graphic units, and each micro-graphic unit is an image to be presented.

6. The imaging film based on the Fresnel lens-formed micro-graphic array structure according to claim 5, characterized in that, The micro-graphic unit includes micro-graphic strokes and / or images, and is arranged in a honeycomb arrangement, a square arrangement, etc., which are periodic regular arrangements, or an irregular aperiodic random arrangement, thereby forming a micro-graphic array.

7. The imaging thin film based on the Fresnel lensified micro-graphic array structure according to claim 6, wherein, The composite structure micro-focusing element array layer is obtained by the following method: After aligning the micro-graphic array with the Fresnel microlens array, only the corresponding Fresnel microlens array structure is fabricated in the micro-graphic array region by lithography technology, that is, the micro-graphic array is Fresnel lensified, and a higher ultraviolet photoresist layer than the composite structure micro-focusing element array is retained in other regions, so that the Fresnel lensified micro-graphic array structure in the pits of the ultraviolet photoresist layer is presented.

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

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

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