KR102043261B1 - Manufacturing method of different kinds lens film and different kinds lens film thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing a lens film and a lens film, the first step of forming a seed pattern by forming a first pattern on a base film by a patterning process, and supplying a first resin on the base film Forming a second lens layer on the first lens layer by a planarization process by supplying a second resin onto the first lens layer and forming a first lens layer by an imprinting process by the seed mold; Method for producing a heterogeneous lens film, characterized in that comprises a third step to the technical gist. As a result, the present invention can implement a heterogeneous lens layer through a planarization process, and allows a flat lens layer to be implemented on the surface to protect the basic lens layer (first lens layer) while improving the resolution and stereoscopic heterogeneous lens film. There is an advantage that can be provided.

Description

Manufacturing method of heterogeneous lens film and heterogeneous lens film produced by the same {Manufacturing method of different kinds lens film and different kinds lens film hence}

The present invention relates to a method for manufacturing a lens film and a lens film, and in particular, to implement a different lens layer through a planarization process to protect the basic lens layer while improving the function of the heterogeneous lens film and a heterogeneous film produced thereby It relates to a lens film.

Looking at the recent development trend of surface light source, the development of direct and edge-type backlight assembly using LED (LED) is active according to the trend of slimmer, smaller and lower power.

LED is a strong point light source, which is suitable for stable lifespan and low power, but it is difficult to change it into a surface light source that must show the shape of a point light source when viewed from other surface light source materials such as TVs and monitors. have.

In general, a diffuser plate and a patterned light guide plate are applied to convert the LED into a surface light source capable of displaying uniform brightness on the front of the display.

Recently, due to the development of a technology for a lens array, in particular a micro lens array (MLA), an optical film in which a microlens array is formed has been developed. It is to perform the function, the shielding of the side blinds and the front condensing function, the technology has been applied to not only 2D display but also 3D display.

On the other hand, the light field 3D technology may be divided into an external device, for example, an external device such as polarized glasses, and a method of generating 3D by itself without using an external device.

In the latter case, 3D can be implemented using Parallax Barrier and micro lens. The use of current advanced photolithographic pattern technology enables more realistic 3D of auto glasses.

The Parallax Barrier method can make the filter transparent, so it is easy to convert between 2D / 3D and mass-produced.It is currently used as the mainstream method. The disadvantage is that you can.

In order to improve the Parallax barrier method, a technique using a microlens can be applied. This microlens refracts light in a specific direction to send different images to different eyes on the left and right sides. Arranged in a constant manner, the image is expressed according to the viewer's angle.

However, the method using a micro lens also requires a user within a certain position to obtain the maximum 3D. Furthermore, discrepancies in focus and observer focusing cause eye fatigue. The greater the depth, the more the eye fatigues.

In order to overcome these limitations, research on full parallax (multi-view & integral imaging) has been actively conducted recently, and it is the most expected technology in autostereoscopic 3D display technology, and it provides constant parallax as well as horizontal parallax. In the viewing angle, a three-dimensional image having a natural and continuous view can be displayed.

As a related art of a microlens array optical film, the lens is formed in a circular structure (Patent Publication No. 10-2011-92372), forming a scattering pattern between the optical pattern (Application No. 10-2011-0096921) And forming an irregular pattern in which a pattern is irregularly formed (Application No. 10-2012-0091641).

In general, the microlens array optical film is coated with a photosensitive resin layer on a surface of a base film, and a photomask is placed on or under the photosensitive resin layer to cure and develop the photosensitive resin layer by ultraviolet irradiation. An optical pattern (microlens) is formed by first forming a master film having an embossed or intaglio master pattern formed thereon, and performing a roll-to-roll or imprinting process by providing an ultraviolet curable resin on the master film, and then removing the master film. Array) is formed to produce an optical film.

The optical film having the optical pattern formed thereon has been applied to the aforementioned full parallax type 3D display as well as the existing 2D display.

In the conventional microlens array, the shape of each lens is generally used in the form of a lenticular lens or a spherical lens.

However, the shape of the lens is easy to deform the shape of the lens due to the protrusion or concave shape in the use environment or commercialization because the bone, protrusions, etc. between the lens is touched or exposed from the outside, the dust between the bones It is not easy to remove or remove it, thereby changing the transparency of the lens to shorten the life of the product.

In addition, this causes light scattering, diffuse reflection, and the like, thereby causing resolution, three-dimensional (depth), decrease in visibility, and the like.

This problem may be a bigger obstacle when applying the full parallax method, and may be an obstacle to commercialization.

The present invention is to solve the above problems, while implementing a different lens layer through a planarization process to protect the basic lens layer while improving the resolution, three-dimensional and visibility and improve the durability of the product and a method of manufacturing a different lens film It aims at providing the heterogeneous lens film manufactured by the above.

In order to achieve the above object, the present invention provides a first step of manufacturing a seed mold by forming a first pattern on a base film by a patterning process, and imprinting by the seed mold by supplying a first resin on a base film. A second step of forming a first lens layer by a process; and a third step of forming a second lens layer on the first lens layer by a planarization process by supplying a second resin on the first lens layer. The manufacturing method of the heterogeneous lens film characterized by the above-mentioned.

In addition, the present invention is a base film, a second lens formed on the base film, the first lens layer formed of a first resin, and the second lens formed on the first lens layer, the second resin is flat surface It is configured to include a lens layer, the first lens layer and the second lens layer has a different lens film, characterized in that the refractive index is different from another technical gist.

The first lens layer and the second lens layer may have different refractive indices according to the types of the first resin and the second resin, and among the first lens layer and the second lens layer, In this case, it is preferable that the high refractive particles are further included in the first resin or the second resin.

Here, the high refractive particles, it is preferable to use a material containing at least one of titanium oxide, tin oxide, zirconia, zinc oxide, magnesium oxide, barium titanate, alumina and silica.

In addition, in order to increase adhesion between the first lens layer and the second lens layer, it is preferable to adjust the reaction rate or degree of curing of the first resin and the second resin.

The first lens layer may be formed of a lenticular or micro lens array, and the second lens layer may have a flat surface or an anti-glare pattern on the surface. It is preferable that this is formed.

In addition, the refractive index of the first lens layer is preferably higher than the refractive index of the second lens layer.

In addition, it is preferable that the difference between the refractive index of the first lens layer and the refractive index of the second lens layer is 0.15 to 0.35.

In addition, the thickness of the first lens layer is 5 ~ 100㎛, the thickness of the second lens layer is preferably 3 ~ 30㎛ from the top of the first lens layer, the valley and the base of the first lens layer It is preferable that the distance between the surfaces of a film forms a base layer at 2-3 micrometers.

In the first step, the photoresist layer is coated on the base film, the photomask is positioned on or below the photoresist layer, and the photoresist layer is patterned by a photolithography patterning process. It is preferable to manufacture a seed mold having a first pattern formed thereon corresponding to the pattern of the first lens layer.

In addition, the planarization process of the third step may be implemented by a planarization roll having a smooth surface or a planarization roll having a second pattern corresponding to the pattern of the second lens layer on the surface. In the planarization process, hard curing is performed after soft curing.

In addition, the planarization process is preferably implemented by a roll-to-roll process.

As described above, the present invention can implement a heterogeneous lens layer through a planarization process, and a flat lens layer is implemented on the surface to protect the basic lens layer (first lens layer) while eliminating diffuse reflection, thereby improving resolution and stereoscopic effect. It is effective to provide a heterogeneous lens film.

In addition, since the shape of the basic lens layer is not exposed to the outside by the flat lens layer on the surface, bones, protrusions, etc. between the lenses are not touched, and thus the shape of the lens can be permanently preserved in the use environment or commercialization. There is no effect between the dust to improve the durability of the product.

In addition, the present invention can be easily adjusted to the refractive index to obtain a higher resolution, three-dimensional image with a three-dimensional effect, can be applied to the optical film basically, there is an effect that can be applied to not only 2D display but also 3D display.

In addition, it can be applied to 3D display of full parallax type and is expected to contribute to its commercialization.

1-Schematic diagram of a method for manufacturing a heterogeneous lens film according to an embodiment of the present invention.
Figure 2-Schematic diagram of a method of manufacturing a heterogeneous lens film according to another embodiment of the present invention.
3 is a view showing a cross-sectional shape of a heterogeneous lens film produced according to an embodiment of the present invention.

The present invention relates to a method for manufacturing a heterogeneous lens film and a heterogeneous lens film manufactured thereby to implement a heterogeneous lens layer through a planarization process to protect the basic lens layer while improving resolution, stereoscopicity and visibility and improving durability of the product. will be.

Hereinafter, with reference to the accompanying drawings will be described in detail for the present invention. 1 is a schematic diagram of a method of manufacturing a heterogeneous lens film according to an embodiment of the present invention, Figure 2 is a schematic diagram of a method of manufacturing a heterogeneous lens film according to another embodiment of the present invention, Figure 3 is Figure is a cross-sectional view of the hetero-lens film produced according to one embodiment.

As shown, a method of manufacturing a heterogeneous lens film according to the present invention includes a first step of manufacturing a seed mold by forming a first pattern on a base film by a patterning process, and supplying a first resin on a base film. Forming a second lens layer on the first lens layer by a planarization process by supplying a second resin on the first lens layer by an imprinting process using a seed mold and supplying a second resin on the first lens layer; It comprises a third step.

The heterogeneous lens in the present invention basically means a structure that forms two or more kinds of lens layers having different shapes or materials or different physical properties.

In the method for manufacturing a heterogeneous lens film according to the present invention, first, a seed pattern is manufactured by forming a first pattern on a base film by a patterning process (first step).

Specifically, the photoresist layer is coated on the base film, the photomask is positioned on or below the photoresist layer, and the photoresist layer is patterned by a photolithography patterning process to form the first lens on the base film. The seed mold having the first pattern corresponding to the pattern of the layer is formed.

The base film may be a transparent or opaque material according to the type of photoresist. That is, a transparent material may be used for the negative photoresist, and a transparent or opaque material may be used for the positive photoresist.

In one embodiment, in the case of using a negative photoresist, it is preferable that a transparent material is used to transmit light in the photolithography process, and also formed of a polymer material to enable the roll-to-roll process.

The base film is a transparent or opaque material, using any one of glass, silicon, polycarbonate, polyethylene terephthalate, acrylic, polystyrene, polymethyl methacrylate.

In particular, as an embodiment of the present invention, polyethylene terephthalate (PET) is used which is inexpensive and has excellent transparency, durability and processability.

A photoresist layer is coated on the base film to perform a patterning process by porolithography, and the coating method is in accordance with a known method.

The photoresist layer may use a positive or negative photoresist according to a working environment or a shape of a pattern. Accordingly, the first pattern of the seed mold may be formed in an intaglio or embossed form with respect to the microlens array pattern.

A seed mold having a first pattern corresponding to a microlens array pattern is formed on the base film by performing a photolithography patterning process of placing a photomask on or below the photoresist layer and patterning the photoresist layer. To produce.

That is, the seed mold according to the present invention is a first pattern and the base film are all formed of a polymer material to provide a soft mold, the soft mold is a continuous, such as roll to roll, while easily releasing in a process to be described later The process has the advantage of being possible.

According to an embodiment of the present invention, when a photoresist layer is coated on a base film, a photomask is placed below the photoresist layer, and the ultraviolet rays are irradiated from the photomask side, the UV-irradiated portion is cured. And the unirradiated portion is left uncured.

Here, in the curing method according to an embodiment of the present invention, a control layer for controlling the path (angle), intensity, reaction rate, etc. of the light source may be further formed between the base film and the photoresist layer and the photomask. In addition, by controlling the photosensitivity of the photocurable photoresist layer, the concentration and type of the developer, the spacing, shape, size, etc. of the mask pattern, it is possible to control the area of the cured or uncured portion inside the photoresist layer.

1, the hardening does not occur only in the hemispheric pattern area by the area covered by the mask pattern of the photomask, but hardening occurs in other areas. The formed seed mold will be formed.

In this case, when the patterning process is performed once more using the seed mold, an inverse embossed pattern (first pattern) is formed. In this case, the seed mold becomes a base mold. That is, the seed mold is a mold that imprints the final product pattern.

When the base mold is to be used, there is no particular limitation on the base film, and both organic and inorganic substrates such as polyethylene terephthalate, polycarbonate, glass, silicon wafers, and the like may be used.

As described above, the base mold may be a seed mold by itself according to the pattern of the microlens array, or in the case of forming a reverse microlens array pattern, the base mold is completely cured on the intaglio pattern on the base mold. Thereafter, the photoresist layer may be further formed on the base film, and the photoresist layer may be further imprinted according to the microlens array pattern. Here, the base film is preferably the above-described polymer material for soft mold production.

That is, the imprinting process may not be performed according to the type of photoresist layer or the microlens array pattern, and the seed pattern of the embossed or intaglio pattern is subjected to the imprinting process once more to manufacture the final seed mold (the first pattern). You can also have

As such, the seed pattern may be embossed or engraved to correspond to the microlens array pattern, which is determined according to the type of the photoresist layer as described above, and FIG. 1 illustrates an embodiment of the present invention. In an embodiment, the first pattern is formed as an intaglio pattern which is an inverse of the pattern of the first lens layer.

On the other hand, according to the photolithography process according to the present invention, it is possible to form a variety of forms of the first pattern which is the seed pattern. For example, any one of polygonal, hemispherical, elliptical and prismatic forms, or a combination thereof, or a portion of these patterns may be merged.

In addition, any one of these polygonal, hemispherical, elliptical, and prismatic patterns, or a combination thereof, may be arranged in a hexagonal shape or in a rectangular shape.

The shape and arrangement of the pattern depends on the efficient arrangement for improving the reliability and optical properties of the microlens array.

Then, the first resin is supplied onto the base film to form a first lens layer by an imprinting process using the seed mold (second step).

The base film may be a flexible or hard material depending on the process environment or application, such as organic or inorganic substrates, such as glass, silicon, acrylic, polyethylene terephthalate, polycarbonate, polypropylene, polyethylene, polystyrene, polymethyl methacrylate, and the like. .

The first resin is supplied onto the base film. The first resin is a material that is cured by ultraviolet rays, and may use a photoresist used in a general photolithography process.

For example, radiation-curable epoxy acrylate, urethane acrylate, polyester acrylate, or a refractive index controlled substituent may be used, and include SU-6, SU-7, or a fluorine-based acrylic resin or fluorine functional group. Used resins, acrylic resins with aromatic functional groups and the like can be used.

The first resin is supplied onto the base film to form a first resin layer, and an imprinting process of hardening after imprinting by placing a seed mold on which the first pattern is formed is placed on the first resin layer.

After the imprinting process, the seed mold is peeled off to form a first lens layer formed of a first resin on a base film and having a reversed phase of the first pattern. The formation of the first lens layer on the base film is also possible by a roll-to-roll imprinting process if the base film and the base film are used as a flexible material.

Here, the curing during the imprinting process may be performed by soft curing according to the type of the first resin and the second resin to be described later, the shape of the lens, and the like. This is to enhance the adhesion between the second lens layer and the first lens layer, which will be described later, in addition to the ease of peeling off from the seed mold. That is, by adjusting the reaction rate or degree of curing of the first resin by partial curing, the adhesive force can be controlled by adjusting the amount of unreacted functional groups.

The first lens layer may be formed of a reverse phase of the first pattern of the seed mold, for example, a lenticular or micro lens array. However, the present invention is not limited thereto, and as described above, one of polygons, hemispherical shapes, ellipses, and prisms, or a combination thereof, or a part of these patterns may be combined.

In addition, the thickness of the first lens layer is formed to 5 ~ 100㎛ according to product specifications or applications, which is formed in consideration of the focal length. In addition, the base layer corresponding to the distance between the valley of the first lens layer and the surface of the base film to be generated by the imprinting process is preferably formed in 2 ~ 3㎛.

The base layer has a thickness adjusted according to the pressure or the shape of the first pattern in the seed mold during the imprinting process, and the presence of the base layer maintains a stable shape without collapsing the shape of the lens.

Then, a second resin is supplied onto the first lens layer to form a second lens layer on the first lens layer by a planarization process (third step).

The second resin may also use a material that is cured by ultraviolet rays similarly to the first resin. Resin listed in the description of the first resin can be used, but a different type of resin than the first resin is used.

The second resin is supplied onto the first lens layer to form a second lens layer made of the second resin by a planarization process.

The planarization process is such that the second lens layer formed on the first lens layer is formed in a flat shape, that is, in a flat shape, and the lower portion of the second lens layer is uniform in the valley of the lens of the first lens layer. Flowing in, the surface is formed in a flat shape.

In order to form the second lens layer, a predetermined pressure is applied during the planarization process, which is controlled according to the type of resin and the thickness of the second lens layer.

For example, the planarization process may be implemented by a planarization roll having a smooth surface as illustrated in FIG. 1, or by a planarization roll having a second pattern corresponding to the pattern of the second lens layer on the surface.

That is, the surface of the second lens layer may be flat or a pattern may be formed on the surface. However, the second lens layer may have a pattern that does not impair the flatness, for example, a pattern in which an anti-glare function is expressed. Can be.

The thickness of the second resin layer is preferably 3 ~ 30㎛ from the top of the first lens layer. If it is thinner than this, the surface flatness will be low, and if it is higher than this, the focal length will be changed and the design of the lens should be performed again. That is, the thickness of the first resin layer and the thickness of the second resin layer are set in consideration of the focal length according to the use or specification of the product.

In this case, as described above, soft curing may be performed to improve adhesion to the first lens layer. This is to improve adhesion by adjusting the surface chemical reactivity of the unreacted functional group and the resin between the first lens layer and the second lens layer, and then hard harden to completely stabilize the shape of the lens. That is, by adjusting the reaction rate or degree of curing of the second resin to improve the adhesive force with the first lens layer.

The planarization process may be implemented by a roll-to-roll process, which is illustrated in FIG. 2.

As shown in FIG. 2, the base film (for example, PET film) on which the first lens layer is formed is wound on a supply roll and continuously unwound, and the heterogeneous lens film according to the present invention is rewound by a collection roll. . The rotational speed of the feed roll and the collection roll is rotated in consideration of the time required for photocuring.

The base film having the first lens layer supplied from the supply roll is supplied to the flattening roll disposed at a specific position by the auxiliary roll. In this case, the second resin is supplied from one side of the flattening roll so that the second resin is supplied onto the first lens layer, and then the base film having the first lens layer formed on the flattening roll is supplied.

The flattening roll may have a flat surface, or may have a pattern that may have an antiglare effect on the surface, and may uniformly between the thickness of the second lens layer and the lens valley of the first lens layer. A constant pressure is applied to form the layer and the curing process is performed.

As described above in the curing process, soft curing may be performed to improve adhesion between the first lens layer and the second lens layer. Then hard curing is performed to stably fix the shape of the lens. Here, a partial curing process such as soft curing and hard curing may be selectively implemented according to the type of resin or the shape of the lens.

As such, a seed mold is formed by a patterning process, a first resin layer is formed on the base film by an imprinting process, and a second resin layer is formed on the first resin layer by a planarization process.

The first resin layer and the second resin layer are formed of different materials to have different physical properties. In particular, in the present invention, the refractive indexes of the first lens layer and the second lens layer are different from each other for refractive index control. It is done.

That is, as the incident light is refracted in a specific direction to achieve a desired resolution and three-dimensional effect, it can be applied to not only a 2D display but also a 3D display.

Preferably, the difference in refractive index between the first resin layer and the second resin layer is formed in the range of 0.15 to 0.35. If the difference is lower than this, the refractive index difference is insignificant, which is insufficient to expect the refractive effect. This difficulty makes the process less reproducible and complicated.

In particular, the refractive index of the first lens layer is preferably higher than the refractive index of the second lens layer, which is to maximize the refractive effect. Depending on the specification and the use of the product may be formed in the opposite direction, in this case, total reflection occurs in the second resin layer.

On the other hand, the first resin and the second resin, as described above, can be used as a material that is cured by ultraviolet light, for example, radiation-curable epoxy acrylate, urethane acrylate, polyester acrylate or a substituent that adjusts the refractive index, etc. And SU-6, SU-7, or a fluorine-based acrylic resin or a resin containing a fluorine functional group, an acrylic resin having an aromatic functional group, and the like, wherein the first resin and the second resin Different types of resin can be used to vary the refractive indices.

Basically, high refractive resin or low refractive resin can be used to make a difference in refractive index, and high refractive resin can be realized by including high refractive particles even if it is not high refractive resin.

For example, the high refractive resin may be formed by dispersing high refractive particles in an acrylic resin having an aromatic functional group, or the low refractive resin may include a fluorine-based acrylic resin or a resin containing a fluorine functional group. Of course, including the high refractive particles in the low refractive resin can be a high refractive resin.

The high refractive particles may be formed of inorganic nanoparticles such as titanium oxide, tin oxide, zirconia, zinc oxide, magnesium oxide, barium titanate, alumina and silica.

The inorganic nanoparticles may have a diameter of 1 to 50 nm, and may be added by modifying the surface of the inorganic nanoparticles to improve dispersibility in the resin. Surface modification of the inorganic nanoparticles is made by a known method, for example, the surface of the nanoparticles may be coated with a polymer or a dispersant, a surfactant, or the like may be added.

In one embodiment of the present invention, the acrylic oligomer 2 to 40 parts by weight, the acrylic monomer 10 to 70 parts by weight, inorganic nanoparticles 1 to 10 parts by weight, initiator 1 to 5 parts by weight, additives 1 to 5 middle parts, each according to the refractive index Adjust the ingredients.

Figure 3 shows a heterogeneous lens film produced according to an embodiment of the present invention.

A convex lens is formed as a first lens layer on a PET film (base film), and a flat lens is formed thereon. The first lens layer has a relatively higher refractive index than the second lens layer, and zirconia nanoparticles are added to the acrylic resin having an aromatic functional group as the first resin.

The refractive index of the first lens layer was 1.65 to 1.7, the refractive index of the second lens layer was observed as 1.4, it was confirmed that the refractive index control is possible.

As described above, the present invention can implement a heterogeneous lens layer through a planarization process, and a flat lens layer can be implemented on the surface to protect the basic lens layer (first lens layer), while easily adjusting the refractive index, and diffuse reflection. By eliminating the has the advantage of improving the resolution, three-dimensional and visibility and improve the durability of the product.

Claims (25)

Supplying a photoresist layer on the base film, and then forming a seed mold by forming a first pattern having a plurality of concave hemispherical shapes to be opened toward the opposite side of the base film by a photolithography patterning process;
Supplying a first resin onto a base film to form a first lens layer having a plurality of convex lenses to expose the base film by an imprinting process by the seed mold; And
The second lens layer of the flat lens on the first lens layer to cover the plurality of convex lenses while supplying a second resin on the first lens layer to fill the valleys between the plurality of convex lenses by a planarization process. To include; a third step;
The first lens layer and the second lens layer of the first lens layer and the second lens layer with respect to light irradiated from an LED unit to sequentially look at the first lens layer and the second lens layer. Method for producing a heterogeneous lens film, characterized in that for passing a different image to the left and right eyes of the person past the first lens layer. delete delete delete delete The method of claim 1, wherein the first lens layer,
Method of producing a heterogeneous lens film, characterized in that formed in a lenticular (Lenticular) or Micro (Micro) lens array. The method of claim 1, wherein the second lens layer,
The surface is flat,
Or an anti-glare (Anti-Glare) pattern is formed on the surface of the manufacturing method of heterogeneous lens film. The method of claim 1, wherein the refractive index of the first lens layer is relatively higher than the refractive index of the second lens layer. The method of claim 1, wherein the difference between the refractive index of the first lens layer and the refractive index of the second lens layer,
Method for producing a heterogeneous lens film, characterized in that 0.15 ~ 0.35. delete delete delete delete delete The method of claim 1, wherein the planarization process,
Method for producing a heterogeneous lens film, characterized in that implemented by a roll-to-roll process. Base film;
A first lens layer formed on the base film and formed of a first resin and formed of a plurality of convex lenses;
And a second lens layer formed on the first lens layer so as to fill between the plurality of convex lenses on the base film, and formed of a second resin to have a flat surface.
The first lens layer has a larger refractive index than the second lens layer,
The second lens layer is thicker in the valleys between the individual convex lenses than at the peaks of the individual convex lenses,
The first lens layer and the second lens layer are totally reflected at a boundary between the first lens layer and the second lens layer with respect to light emitted from the LED unit and passing through the first lens layer, so that the left and right eyes of a person Heterogeneous lens film, characterized in that to send another image. The method of claim 16, wherein the first lens layer,
Heterogeneous lens film, characterized in that formed by a lenticular (Lenticular) or Micro (Micro) lens array. The method of claim 16, wherein the second lens layer,
Heterogeneous lens film, characterized in that the anti-glare (Anti-Glare) pattern is formed on the surface. delete delete delete The method of claim 16, wherein the difference between the refractive index of the first lens layer and the refractive index of the second lens layer,
Heterogeneous lens film, characterized in that 0.15 ~ 0.35.




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