KR20130002793A - Micro lens film and backlight unit assembly comprising the same - Google Patents

Abstract

The present invention relates to a microlens film and a backlight unit assembly including the same. By specifying a diameter, a height, and a filling rate of a microlens formed on the microlens film, the microlens has improved brightness and transmittance while maintaining haze compared to a conventional microlens film. Relates to a film and backlight unit assembly.

Description

Micro Lens Film and Backlight Unit Assembly Comprising the Same}

The present invention relates to a micro lens film (MLF) used in a backlight unit assembly and a backlight unit assembly including the same.

In the display device represented by the liquid crystal display device, high front luminance is required. Therefore, an optical lens film for improving front luminance may be provided in the backlight unit assembly used in the liquid crystal display device.

A micro lens film is mentioned as an optical lens film for backlight unit assemblies for improving front brightness.

The microlens film may have a plurality of convex lenses (microlenses) on one surface thereof, and the microlens film used for the backlight unit assembly collects the diffused light from the light source by the plurality of microlenses and emits front luminance. Improve.

In general, the microlens formed on the microlens film has a hemispherical shape, and the higher the fill factor, the higher the height of the hemisphere, and the higher the luminance.

That is, since the brightness of the backlight unit assembly may vary according to the shape of the microlens formed on the microlens film, it is necessary to improve the properties of the microlens film by developing various types of microlenses.

The present invention optimizes the diameter, height, and fill factor of the microlenses formed on the microlens film to improve the brightness of the backlight unit assembly to which the microlens film is applied, thereby improving the transmittance along with the luminance of the backlight unit assembly. An object of the present invention is to provide a micro lens film and a backlight unit assembly including the same.

Accordingly, the present invention is a first preferred embodiment, the base layer 10; A micro lens layer 20 having a plurality of micro lenses arranged on one surface of the base layer; And a resin coating layer 30 formed on an upper surface of the micro lens layer, wherein the micro lens has a ratio of diameter to height (diameter / height) of 2 to 5 and a filling rate of 25 to 60%. Provide a micro lens film.

The microlens layer according to the embodiment may be one selected from the group consisting of ultraviolet curable resins, thermosetting resins, and thermoplastic resins.

The coating layer according to the embodiment may be selected from the group consisting of Acrylate, Urethane, Epoxy and mixtures thereof.

The refractive index difference ΔR between the resin coating layer and the microlens layer according to the embodiment may be 0 <ΔR <0.1.

The haze / transmittance (Hz / TT) of the microlens film according to the embodiment may be 0.70 to 1.55.

The invention also provides a second preferred embodiment, comprising: a first prism film; A second prism film formed on the first prism film; And the micro lens film formed on the second prism film.

The first prism film and the second prism film according to the embodiment may both be a composite prism film, or the first prism film and the second prism film may be a composite prism film and a prism film, respectively.

1 is a longitudinal sectional view of a micro lens film of the present invention.
2 is a perspective view of a backlight unit assembly of the present invention.
3 is a longitudinal sectional view of the prism film (a) and the composite prism film (b) used in the backlight unit assembly of the present invention.
4 is a diameter (a) of a micro lens formed on a micro lens film according to a comparative example; Fill factor (b) of the microlenses; And microlens film cross section (c).
5 is a diameter (a) of a micro lens formed on the micro lens film according to the embodiment; Fill factor (b) of the microlenses; And microlens film cross section (c).
<Short description of drawing symbols>
10: base material layer 20: micro lens layer
30: resin coating layer
100: first prism film 200: second prism film
300: micro lens film
101: base material layer (of prism film) 102: prism layer
103: light diffusion layer

Hereinafter, the present invention will be described in more detail.

The present invention relates to a microlens film formed in a microlens film (MLF), in particular, a microlens film having improved luminance and transmittance according to the height of the microlens.

1, the micro lens film according to the present invention is a base layer 10; A micro lens layer 20 having a plurality of micro lenses arranged on one surface of the base layer; And a resin coating layer 30 formed on an upper surface of the micro lens layer, wherein the micro lens has a diameter-to-height ratio (diameter / height h) of 2 to 5 and a filling rate. (fill factor) is characterized in that 25 to 60%.

Here, the resin coating layer 30 is formed in the form of filling between the spaces between the micro lens, the diameter (l) and height (h) of the micro lens may be determined by the surface formed by the resin coating layer 30, the diameter (l) 20-70 micrometers, Preferably it is 25-65 micrometers, and height h may be 12-35 micrometers. In addition, the filling rate represents the ratio of the area occupied by the microlens to the total area of the microlens layer.

If the ratio of the diameter to the height of the micro lens (diameter / height) is less than 2, there is a problem in that the effect of increasing the brightness is insignificant. If the ratio exceeds 5, the transmittance is high and the lower pattern or the mura may be seen. In addition, when the filling ratio of the microlenses is less than 25%, there is a problem in that a lower pattern or a mura is visible due to high transmittance, and when it is more than 60%, light is scattered more than necessary and luminance is lowered.

The base layer may have a thickness of about 10 to 500 μm, and any base film may be used as long as it is a film made of a transparent resin used for an optical sheet such as a prism sheet or a prism film. Examples thereof include polyethylene terephthalate film, polycarbonate film, polypropylene film, polyethylene film, polystyrene film or polyepoxy film.

The microlens layer may be a light transmissive polymer material such as an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin, and the like, for example, an ultraviolet curable acrylic resin, an unsaturated fatty acid ester, an aromatic vinyl compound, an unsaturated fatty acid and its derivatives, and an unsaturated compound. Unsaturated dibasic acid and its derivatives, vinyl cyanide compounds such as methacrylonitrile, and the like can be used.

The resin coating layer is formed on the upper surface of the microlens layer, so that the microlens film of the present invention can reduce the height and filling rate of the microlens so that the brightness and transmittance can be improved while maintaining the same level of haze with respect to the conventional microlens film. Play a role.

The resin coating layer may be one selected from the group consisting of Acrylate, Urethane, Epoxy, and mixtures thereof, and thus, the refractive index may be adjusted through proper blending, so that brightness and concealment may be properly implemented.

In addition, the resin coating layer may be one and the refractive index is not the same as the micro lens layer, the refractive index difference (ΔR) of the resin coating layer and the micro lens layer may be 0 <ΔR <0.1. By forming the resin coating layer such that 0 <ΔR <0.1, the transmittance of the microlens film can be improved while exhibiting higher haze characteristics in the same lens structure through the difference in refractive index between the two materials. Increasing the height can prevent the luminance deterioration phenomenon

The base layer and the microlens layer of the above-described microlens film may be manufactured according to the indirect engraving method using a UV curing crude liquid in consideration of moldability and releasability. This indirect engraving method is a well-known process method in the field to which the present invention belongs will not be described in detail.

After forming a base layer using a soft mold or a metal master mold and a micro lens layer formed on the base layer, a resin coating layer is formed on the upper surface of the micro lens layer through a post coating process, wherein the post coating process is a UV binder. A resin coating layer may be formed using a resin or a thermosetting binder resin, and a microlens film may be manufactured by forming a resin coating layer by a gravure coating method.

Compared to the microlens film which does not include the conventional resin coating layer, the microlens film manufactured as described above maintains the same level of haze while improving the transmittance of light from the bottom to conceal luminance while concealing the lower BLU pattern and Mura. There is an effect that can be improved. Specifically, the micro lens film according to the present invention may have a haze / transmittance (Hz / TT) of 0.70 to 1.55.

Meanwhile, when the microlens film according to the present invention is applied to the backlight unit assembly, as shown in FIG. 2, the first prism film 100; A second prism film 200 formed on the first prism film; And a micro lens film 300 formed on the second prism film.

By placing two prism films having a light converging structure below the micro lens film, luminance can be improved without using a film using expensive polarized light. In addition, it is possible to ensure the concealability of the pattern due to the effect that the phase is separated by laminating the lower prism film. Specifically, in the backlight unit assembly having the structure as described above, when both the first prism film and the second prism film are composite prism films, or the first prism film is a composite prism film, and the second prism film is a prism film , The microlens film according to the present invention may exhibit a brightness enhancement effect of about 5 to 10% compared to the conventional microlens film.

At this time, the prism film used as the second prism film is a prism film having a light collecting function commonly used in the art, for example, the base layer 101 and the prism layer 103 formed on one surface of the base layer It may have a structure to include (Fig. 3 (a)). In addition, the composite prism film used as the first prism film or the second prism film is a prism film having both a light condensing function and a diffusing function. For example, the base layer 101 and the light diffusing layer formed on one surface of the base layer ( 102 and a prism layer 103 formed on an upper surface of the light diffusion layer (FIG. 3B). The light diffusing layer may be formed by dispersing light diffusing particles in a binder resin, and the binder resin may be formed of a resin having good adhesion with a base layer and having good compatibility with the light diffusing particles which are sprayed, that is, light diffusing particles. It is possible to use evenly dispersed in the resin evenly separated or precipitate is not good, and organic particles or inorganic particles may be used as the light diffusing particles. Binder resins having such properties include unsaturated polyesters, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, and hydroxyethyl Methacrylate hydroxypropyl methacrylate, hydroxyethyl acrylate, acrylamide, methrol acrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate, 2-ethylhexyl acryl Homopolymer of rate. Acrylic resins, such as these copolymers or ternary copolymers, urethane resin, epoxy resin, melamine resin, etc. are mentioned. In addition, the organic particles used as the light diffusing particles are methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylamide, methrolacrylamide, glycidyl methacryl Acrylic particles of acrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate, 2-ethylhexyl acrylate homopolymer or copolymer, and olefin particles such as polyethylene, polystyrene and polypropylene, and acrylic and olefin air Multi-layered multi-component particles formed by forming the particles of the base body and the homopolymer and then covering the layers with other monomers, and the inorganic particles include silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, magnesium fluoride, etc. Can be mentioned.

Hereinafter, the present invention will be described in detail with reference to the following Examples, the present invention is not limited by the Examples.

Examples 1-10

A microlens film having a diameter, a height, and a filling rate of the microlenses described in Table 1 was prepared by the following method.

511RM (Minutatech Co., Ltd.) was coated as a photocurable crude liquid on GB7000 sheet having a glass beads having a bead diameter of 60 to 70 μm and cured at a primary UV light amount of 100 mJ / cm 2 to form a crude liquid layer. Then, after the mold liquid layer formed was released, a soft mold was prepared by irradiating secondary UV light amount of 1000 mJ / cm 2. The soft mold was applied to an indirect engraving process to prepare a microlens film. In this case, KR-30 (Minuterita Co., Ltd.) was used as the photocurable crude liquid, and the curing was performed under the same UV curing conditions as those of the soft mold.

Then, the resin coating layer was formed with the binder of Table 1, and the micro lens film was produced (FIG. 5).

300 parts by weight of methyl ethyl ketone and 300 parts by weight of toluene were diluted with respect to 100 parts by weight of 511RM (Minutita Tech Co., Ltd.). It was formed by curing through the coating so that the height of the lens layer is properly exposed. In this case, the difference in refractive index between 511RM formed and KR30KR-30 (Minutatec Co., Ltd.) used to form MLF is about 0.02.

Also, after diluting 300 parts by weight of methyl ethyl ketone and 300 parts by weight of toluene with respect to 100 parts by weight of KR-30 (Minuta Tech Co., Ltd.), the solvent was dried by applying a coating solution using gravure on the upper surface of the lens of MLF. Cured by irradiation with UV light amount was formed by applying so that the height of the lens layer is properly exposed. The gravure coating and the lens layer were adjusted using the same product KR-30KR-30 (Minutitec Co., Ltd.) to adjust the height of the lens layer without difference in refractive index.

Comparative Example 1

A microlens film was prepared in the same manner as in Example 1 except that the resin coating layer was not formed (FIG. 4).

Comparative Examples 2 to 11

A microlens film was prepared in the same manner as in Example 1 according to the diameter, height, and filling rate of the microlenses described in Table 1.

Luminance, transmittance, and haze were measured using the microlens films prepared in Examples and Comparative Examples, and the results are shown in Table 2.

(1) luminance

Luminance was measured using Topcon's BM-7, and the values were removed except for the reflective sheet and diffuser in the backlight unit (32 inches), and the LC217 prism film was placed on the bottom of Kolon's LF343 composite film. After mounting, the optical lens films according to Examples and Comparative Examples were loaded one by one, and each luminance was evaluated as a relative value when the luminance of Comparative Example 1 was 100.

(2) Permeability and Haze Specific

To measure according to JIS K 7136 standard, using Nippon Denshoku's NDH2000 equipment, the light source incidence part is placed on the back to obtain the measured value.

(3) hiding power

After the 22-inch BLU is turned on, the microlens films of Examples and Comparative Examples are placed, and then the degree of light guide plate pattern is reflected and evaluated by exponentiation.

5 4 3 2 1

High hiding power (pattern poet) Low hiding power (pattern poet)

Micro Lens Diameter (μm) Micro Lens Height (μm) Micro lens
Diameter / height Charge rate (%) Resin coating layer Binder resin Refractive index difference Comparative Example 1 60 30 2 65% - - Comparative Example 2 45 15 3 15% KR30
Minuta Tech Co., Ltd. 0.00 Comparative Example 3 45 10 4.5 15% KR30
Minuta Tech Co., Ltd. 0.00 Comparative Example 4 45 20 2.25 15% KR30
Minuta Tech Co., Ltd. 0.00 Comparative Example 5 45 15 3 70% KR30
Minuta Tech Co., Ltd. 0.00 Comparative Example 6 45 10 4.5 70% KR30
Minuta Tech Co., Ltd. 0.00 Comparative Example 7 45 20 2.25 70% KR30
Minuta Tech Co., Ltd. 0.00 Comparative Example 8 45 5 9 15% KR30 0.00 Comparative Example 9 45 5 9 70% KR30
Minuta Tech Co., Ltd. 0.00 Comparative Example 10 45 25 1.8 15% KR30
Minuta Tech Co., Ltd. 0.00 Comparative Example 11 45 25 1.8 70% KR30
Minuta Tech Co., Ltd. 0.00 Example 1 45 15 3 52% KR30
Minuta Tech Co., Ltd. 0.00 Example 2 45 10 4.5 52% KR30
Minuta Tech Co., Ltd. 0.00 Example 3 45 20 2.25 52% KR30
Minuta Tech Co., Ltd. 0.00 Example 4 45 15 3 52% 511RM
Minuta Tech Co., Ltd. 0.02 Example 5 45 10 4.5 52% 511RM
Minuta Tech Co., Ltd. 0.02 Example 6 45 20 2.25 52% 511RM
Minuta Tech Co., Ltd. 0.02 Example 7 30 10 3 52% KR30
Minuta Tech Co., Ltd. 0.00 Example 8 60 20 3 52% KR30
Minuta Tech Co., Ltd. 0.00 Example 9 30 10 3 52% 511RM
Minuta Tech Co., Ltd. 0.02 Example 10 60 20 3 52% 511RM
Minuta Tech Co., Ltd. 0.02

Relative luminance (%) Haze / transmittance Concealability Comparative Example 1 100% 87.5 / 62.8 (= 1.39) 5 Comparative Example 2 110% 45.2 / 93.5 (= 0.48) One Comparative Example 3 112% 41.0 / 94.6 (= 0.43) One Comparative Example 4 109% 57.7 / 89.6 (= 0.64) One Comparative Example 5 94% 65.3 / 63.7 (= 1.03) 2 Comparative Example 6 92% 72.5 / 75.2 (= 0.98) 2 Comparative Example 7 95% 86.4 / 59.3 (= 1.46) 4 Comparative Example 8 102% 78.2 / 90.5 (= 0.86) 2 Comparative Example 9 97% 82.1 / 75.3 (= 1.09) 3 Comparative Example 10 99% 70.5 / 85.5 (= 0.82) 3 Comparative Example 11 98% 84.6 / 61.2 (= 1.38) 5 Example 1 111% 92.9 / 93.5 (= 0.99) 4 Example 2 114% 86.5 / 95.8 (= 0.90) 3 Example 3 104% 84.5 / 91.2 (= 0.93) 5 Example 4 110% 93.5 / 94.1 (= 0.99) 5 Example 5 114% 87.9 / 96.1 (= 0.91) 4 Example 6 104% 85.9 / 90.9 (= 0.95) 5 Example 7 106% 84.5 / 97.5 (= 0.87) 3 Example 8 109% 85.2 / 98.9 (= 0.86) 3 Example 9 106% 85.6 / 97.6 (= 0.88) 4 Example 10 109% 86.6 / 98.9 (= 0.88) 4

As a result of evaluation of physical properties of the microlens films prepared in Comparative Examples and Examples, when the diameter / height value of the microlenses formed on the microlens films was 2 to 5 and the filling rate was satisfied to 20 to 60% (the implementation Examples 1 to 10, it can be seen that compared with the conventional microlens film (Comparative Example 1) in which the resin coating layer is not formed, the luminance characteristic is improved, and the transmittance is improved while the reduction of the haze is minimized. Concealment was also maintained at the same level.

Claims (7)

A base layer;
A micro lens layer having a plurality of micro lenses arranged on one surface of the base layer; And
As a micro lens film comprising a resin coating layer formed on the upper surface of the micro lens layer,
The micro lens
The ratio of diameter to height (diameter / height) is 2 to 5,
Micro-lens film, characterized in that the fill factor (25 to 60%).
The method of claim 1,
The microlens film is characterized in that the material is selected from the group consisting of an ultraviolet curable resin, a thermosetting resin and a thermoplastic resin.
The method of claim 1,
The resin coating layer is a micro lens film, characterized in that the material is selected from the group consisting of Acrylate, Urethane, Epoxy and mixtures thereof.
The method of claim 1,
The refractive index difference (ΔR) of the resin coating layer and the microlens layer is 0 <ΔR <0.1, wherein the microlens film.
The method of claim 1,
Haze / transmittance (Hz / TT) is a micro lens film, characterized in that 0.70 ~ 1.55.
A first prism film;
A second prism film formed on the first prism film; And
A backlight unit assembly comprising the micro lens film of any one of claims 1 to 5 formed on the second prism film.
The method according to claim 6,
And the first prism film and the second prism film are both composite prism films, or the first prism film and the second prism film are composite prism films and prism films, respectively.

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