KR20070091519A - Light scattering film for direct-in and embedded backlight module - Google Patents

Abstract

A light scattering film for direct-in and embedded backlight module is provided to enhance final brightness by preventing a dark zone at a position of an LCD(Liquid Crystal Display) panel corresponding to a position of a light source and emitting uniformly light. A light scattering film is used in a backlight module having at least one light source. The light scattering film includes a base layer(10), a diffusion layer(11), and an antistatic adhesion prevention layer(12). The base layer includes two opposite sides. The diffusion layer is formed on one side of the base layer. The antistatic adhesion prevention layer includes a first surface formed on the other side of the base layer, and a second surface having at least one optical path control unit(123). The optical path control unit is arranged with respect to the arrangement of the light source. The light of the light source is applied directly to the antistatic adhesion prevention layer or is controlled by the optical path control unit in order to control partially the optical path of the light and to apply the controlled light to the antistatic adhesion prevention layer. The controlled light is emitted through the base layer and the diffusion layer.

Description

Light scattering film for direct-in and embedded backlight module

1 is a cross-sectional view of a conventional direct backlight module;

FIG. 2 is a graph showing a relationship between a position and light emission luminance between light sources of FIG. 1;

3 is a cross-sectional view of a conventional immersion light backlight module;

4 is an overall cross-sectional view of a light scattering film according to an embodiment of the present invention,

5 is a view showing the entire cross-section of the optical path adjusting unit deposited on the light scattering film according to an embodiment of the present invention,

6 is an overall cross-sectional view of a direct light type backlight module using a light scattering film according to an embodiment of the present invention,

7 is an overall cross-sectional view of a light-sensitive backlight module using a light scattering film according to an embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

10: base material layer 20: diffusion layer

12: antistatic adhesive layer 111: adhesive

112: organic light scattering particles 113: inorganic fine particles

121: adhesive 122: organic light scattering particles

123: optical path adjusting unit

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a light scattering film, a method of manufacturing the same, and a display device using the same, and more particularly, to a light scattering film used in a direct light type or a back light type backlight module of a flat panel display such as a liquid crystal display (LCD). will be.

Recently, a large and large conventional cathode ray tube (CRT) display device is gradually replaced by a flat panel display (FPD), and a liquid crystal display device having advantages of low power consumption, full color, light weight, and portability ( LCD) has become the mainstream of the market. Typically, in order to solve the problem that the liquid crystal itself does not emit light, a backlight module having a light source is disposed on the rear surface of the liquid crystal panel. The backlight module uniformly introduces the light emitted from the light source into the liquid crystal panel. After the light passes through the liquid crystal, the backlight module is displayed as an image on the LCD to transmit data to the eyes of the user / viewer.

Conventional backlight modules may be classified into edge lighting, direct-in light, and embedded lighting according to the position of the light source. The photometric backlight module has a light source installed at the side end, and is particularly used for mobile phones, PDAs, and notebooks because it is light, thin, narrow, and has low power consumption. However, due to the limitation of the thickness of the light guide plate in the photometric backlight module, the size of the light source placed on the side end is limited, so that a sufficient light source cannot be provided in a large LCD and can be used only in a medium size or a small size backlight module. In the direct-type and sub-type backlight module, a plurality of light sources are stacked directly under the liquid crystal panel, and light is emitted to the front upper part. Although it requires a large space and heavy weight, it can be provided with a sufficient light source has the advantages of high brightness, wide viewing angle, high light utilization efficiency. Therefore, it can generally be used for large sized backlight modules such as LCD monitors and LCD TVs.

1 is a view showing a conventional direct-beam backlight module, from the bottom up to a reflective sheet 2, a plurality of light sources 3, a light guide plate 4, a diffusion sheet 1 and a brightness enhanced film 5 ) Is stacked. This module is combined with the reflective polarizing sheet 6 and the liquid crystal panel 7 to make the LCD. In such a backlight module, the light source 3 may be a linear, U-shaped, or other continuously bent lamp, which is placed between the appropriate spaces. Light is emitted from the light source 3, and the brightness is increased by the light guide plate 4. Next, light is emitted to the diffusion sheet 1, and the light is uniformly diffused by the refraction and scattering effects generated by the diffusion particles in the diffusion sheet 1. Next, a conventional film prism mechanism 5 that can fix the direction of light is used, and the light is collected by refraction and reflection so as to increase the brightness toward the front. Finally, before the light enters the liquid crystal panel 7, a reflective polarizing sheet 6 is further provided to increase the luminance at the front and wide the viewing angle. The bottommost reflective sheet 2 can reflect the light reflected to the bottom through the diffusion sheet 1 back to the diffusion sheet 1 to increase the light utilization efficiency of the light source 3.

3 is a view illustrating a conventional immersion light backlight module, in which a reflective sheet 2, a flat plate optical plate 8 having a plurality of light sources 82, and a diffusion layer 1 are stacked from the bottom. This module is combined with the reflective polarizing sheet 6 and the liquid crystal panel 7 to make the LCD. In such a backlight module, the light source 82 may be a linear or dot-shaped LED, or other light source in other forms, and is placed in the support 81 of the glass or acrylic plate. Light is emitted from the light source 82 directly to the diffusion sheet 1, and the light is uniformly diffused by the refraction and scattering effects generated by the diffusion particles in the diffusion sheet 1. Since this light emitting method emits light directly, the front luminance increases considerably. Before the light enters the liquid crystal panel 7, a reflective polarizing sheet 6 is additionally provided to increase the brightness at the front and wide the viewing angle. The bottommost reflective sheet 2 can reflect the light reflected to the bottom through the diffusion sheet 1 back to the diffusion sheet 1 to increase the light utilization efficiency of the light source 82.

In such a direct-beam and sub-light backlight module, the liquid crystal panel 7 has a high luminance above the light source vertically because the vertical direction of the light source 3, 82 is the emission direction of the light, but the light source 3, 82 At the top between the spaces, the brightness is low. Referring to FIG. 2, this phenomenon occurs due to the light source arrangement in the liquid crystal panel 7, resulting in a light-dark zone.

There are two main ways to solve this problem. First, referring to FIG. 1, the dark zone phenomenon can be reduced by increasing the distance between the light source 3, the light guide plate 4, or the diffusion layer 1. However, lengthening the length of the light source 3 with other elements not only reduces the luminance but also increases the thickness of the entire backlight module. This problem is in conflict with the demand for lighter, thinner and more efficient light utilization of the backlight module.

Second, a dark zone phenomenon may be formed by scattering light by forming a recess or another pattern on the light guide plate 4 or by directly adding a fluorescent material to the diffusion sheet 1 unevenly without using the light guide plate 4. To reduce it.

However, these two methods have a complicated problem in the manufacturing process, and even though they can be technically solved, the cost is increased so that it cannot be applied to mass production.

Therefore, in the direct backlight module, it is necessary to solve the dark zone problem as described above without degrading the optical performance, increasing the thickness of the module, and increasing the cost.

This requirement of the present invention can be satisfied.

An object of the present invention has the effects of light reflection, light scattering, light diffusion, condensing, and mixing, and the dark zone is not formed at the position of the liquid crystal panel corresponding to where the light source is located, so that the light is uniformly emitted to increase the light emission luminance. It is to provide a light scattering film.

It is still another object of the present invention to provide a method for producing the above-described wah film having light reflection, light scattering, light diffusion, condensing, and converging effects. It is intended to provide a method that can be easily introduced.

Another object of the present invention is to provide a backlight module with the above-described film having light reflection, light scattering, light diffusion, condensing, and mixing effects, and to provide a display device manufactured thereby. Since the backlight module employs the scattering film, the display device manufactured by the backlight module has excellent light emission luminance without increasing the volume and cost of the backlight module, and thus the display device manufactured by the backlight module can obtain more excellent output effect.

According to one aspect of the invention, the and film used in the direct-beam or immersion type backlight module is provided with at least one light source, the base film having two opposite sides; A diffusion layer formed on one side of the base layer; And an antistatic adhesive layer comprising a first surface formed on the other opposite surface of the substrate layer and a second surface having at least one optical path adjustment unit deposited in association with the arrangement of the at least one light source. The light emitted from the light source is directly incident on the antistatic adhesion layer, or a part of the optical path of the light is adjusted by the at least one optical path adjustment unit to enter the antistatic adhesion layer, and is emitted through the base layer and the diffusion layer. .

According to another aspect of the invention, the method for producing the above and the film used in the direct light or immersion type backlight module comprises the steps of providing a transparent or translucent layer as the substrate layer, and two opposite sides of the transparent or translucent layer Respectively forming a diffusion layer and an antistatic adhesive layer, wherein the antistatic adhesive layer has a first surface and a second surface, and the first surface is connected to the transparent or translucent layer, and the second antistatic adhesive layer Forming at least one optical path adjustment unit on the surface.

According to another aspect of the present invention, the light scattering film as described above is used in the backlight module.

According to another aspect of the invention, to provide a backlight module using the light scattering film as described above to the display device.

The light-scattering film used for a direct light type or a immersion type backlight module includes a base material layer, a diffusion layer, and an antistatic adhesion prevention layer. The diffusion layer is formed on one side of the substrate layer. One surface of the antistatic adhesive layer is formed on the other side of the base layer. The other surface of the antistatic adhesive layer is provided with at least one light path adjusting unit installed to roughly correspond to at least one light source arrangement used in the backlight module. In operation, light emitted from at least one light source in the backlight module can be incident directly into the antistatic anti-stick layer, or some of the light is incident to the anti-static anti-stick layer after being scattered by at least one optical path control unit. Can be. Next, light exits the substrate layer and the diffusion layer and has a uniform distribution.

The base layer may be made of a polymer film, but may include PET, but is not limited thereto. The diffusion layer may be made of a polymer resin, and may include a PMBA having a light condensing function (ie, providing high optical brightness) and providing fine surface roughness and uniform light scattering effect. It is not limited. The antistatic adhesion layer may be made of a polymer resin, and may include, but is not limited to, PMMA, to prevent contaminants from sticking during the assembly process of the module. The optical path adjusting unit may be screen dot printed, and anti-ultraviolet ink may be used, but is not limited thereto.

4 shows a preferred embodiment of the light scattering film 1 ′ used in the backlight module of the present invention. The light scattering film 1 ′ includes a base layer 10, a diffusion layer 11, and an antistatic antistatic layer 12. The diffusion layer 11 is formed on one side of the substrate layer 10, and the antistatic adhesive layer is formed on the other surface of the substrate layer 10. The upper surface of the antistatic adhesive layer 12 is bonded to the base layer 10, the bottom surface is provided with a plurality of optical path adjustment unit 123.

In this embodiment, the material of the base layer 10 may be a transparent or translucent resin film, PET, TAC, PEN, polymalonate, polyimide, polyether, polycarbonate (polycarbonate), polyamine (polyamine), polyethylene (polyethylene), polypropylene (polypropylene), (polyvinylalcohol) or an equivalent thereof is preferably selected. 25-300 micrometers is preferable and, as for the thickness of the said resin film, 50-200 micrometers is more preferable.

The diffusion layer 11 is composed of diffusion particles composed mostly of organic light scattering particles 112 and inorganic fine particles 113, and an adhesive 111 fixing the diffusion particles to the base layer 10.

The material of the adhesive may be a thermoplastic polymer resin, and may be (meth) acrylate, polyester, polycarbonate, polystyrene or polymethyl pentene or equivalents thereof. It is preferably selected from monomers or polymers. The monomer or polymer of the (meth) acrylate is selected from polymehyl (meth) acrylate (polymehyl (meth) acrylate) or polyethyl (meth) acrylate (polyethyl (meth) acrylate), etc. Preferably, the polyester (polyester) is preferably selected from polyethylene terephthalate (polyethylene terephthalate) or polypropylene terephthalate (polypropylene terephthalate). The weight percentage of the adhesive 111 in the diffusion layer 11 may be 10 to 90% by weight, more preferably 40 to 80% by weight.

The material of the organic light scattering particles 112 is PMMA, polymethoxy benzyl acetate (PMBA), or PVC, or an equivalent thereof. The weight percentage of the organic light scattering particles 112 in the diffusion layer 11 may be 10 to 90% by weight, more preferably 40 to 80% by weight.

The material of the inorganic fine particles 113 is preferably selected from SiO 2, Al 2 O 3, silicon or equivalents thereof. The weight percentage of the inorganic fine particles 113 in the diffusion layer 11 may be 30 to 90% by weight, more preferably 40 to 90% by weight.

In this embodiment, the adhesive 111 is 10 to 30% by weight of polymethyl (meth) acrylate in the diffusion layer 11 and 10 to 30% by weight of polyethylene in the diffusion layer 11 Terephthalate (polyethylene terephthalte). The organic light-scattering particle 112 is composed of 15 to 40% by weight of PMMA in the diffusion layer 11 and 10 to 30% by weight of PMBA in the diffusion layer (11). The inorganic fine particles 113 are composed of 10 to 40 wt% of SiO 2 in the diffusion layer 11 and 10 to 30 wt% of silicon in the diffusion layer 11. The thickness of the diffusion layer 11 is preferably in the range of 15 to 40 µm.

The structure of the antistatic adhesive layer is basically similar to the diffusion layer, and includes a plurality of diffusion particles mainly composed of organic light scattering particles 122 and an adhesive 121 fixing a plurality of diffusion particles to the base layer 10. . The difference lies in the ratio of the diffusion particles and the adhesive, the thickness of the antistatic adhesion layer 12, and the optical path adjusting unit 123 provided on the bottom of the antistatic adhesion layer 12.

The antistatic adhesive layer 12 is formed of diffusion particles protruding from the surface of the adhesive 121. When the antistatic adhesive layer 12 is in contact with another component, contact is made in the protruding diffusion particles, and thus a gap is generated between the rest of the antistatic adhesive layer and the other component to function as an antistatic adhesive layer. do.

The weight ratio of the adhesive 121 in the antistatic adhesive layer 12 is 60 to 95% by weight, more preferably 70 to 90% by weight. The weight ratio of the organic light scattering particles 122 is 5 to 40% by weight, more preferably 10 to 30% by weight.

In this embodiment, the adhesive 121 is 10 to 70% by weight of polymethyl (meth) acrylate in the antistatic adhesive layer 12, and in the antistatic adhesive layer 12 10 to 50% by weight of polyethylene terephthalate (polyethylene terephthalate). The organic light scattering particles 122 are made of PMMA having 10 to 30% by weight in the antistatic adhesive layer 12. The thickness of the antistatic adhesive layer 12 is preferably in the range of 10 to 25㎛.

The light path adjustment unit 123 is attached to the bottom surface of the antistatic adhesion layer 12 and usually coincides with the spatial distribution of the backlight module light source. This spatial distribution is obtained based on the light source attached to the backlight module using the scattering film 1 'of the present invention. As an example, when looking at the direct-light backlight module (FIG. 1), the light source 3 is first arranged in an appropriate space between the reflective sheet 2 and the light guide plate 4, and then the light guide plate 4 is removed from the light source. The transmitted image is exposed and developed at high resolution using a charge coupled device (CCD) or a chroma spectrometer. Thus, a spatial distribution graph having a dark zone, that is, a luminance spatial distribution graph is obtained. Next, in order to design the layout of the optical path adjusting unit 123, a graph is converted into a mirrored picture file using a computer program (such as Photoshop). The optical path adjusting unit 123 may be formed on the bottom surface of the antistatic adhesion layer 12 using the following method in accordance with the above arrangement. However, it is not limited only to the following method.

Method 1: As shown in Fig. 4, dot printing using anti-ultraviolet ink is used to make a non-light-permeation or partial-light optical path adjusting unit 123.

Method 2: The optical path adjusting unit 123 of another surface type through a manufacturing method such as coating, vacuum deposition, ion sputtering, or the like, as shown in FIG. 5, using a translucent material including but not limited to PC. In this case, the shape of the surface may be an irregular V-shaped optical path adjusting unit 1231 or an irregular R-shaped optical path adjusting unit 1232.

Method 3: The optical path adjusting unit 123 is combined by combining Method 1 and Method 2 described above.

As described above, the following methods can be used to produce the light scattering film 1 'in this embodiment. First, after placing the transparent substrate used as the substrate layer 10 in the container, the ultrasonic vibration is applied and the substrate layer 10 is heated to clean. Next, after placing the substrate layer 10 in a coating station, the material constituting the diffusion layer 11 is placed in the coating station. The station operates to attach material to one side of the transparent substrate. Next, after coating, the semifinished product is dried for about 1 to 15 minutes at 75 to 125 ° C. in an oven maintaining a constant temperature and humidity. When it is confirmed that the thickness and physical properties are satisfied, the same process is repeated for the opposite side of the substrate 10. That is, the substrate layer 10 is located in the coating station, and the material constituting the antistatic adhesive layer 12 is placed in the coating station and the material is attached to the opposite side of the transparent substrate. The resulting antistatic adhesive layer 12 has two surfaces, and an optical path adjusting unit 123 is later stacked on the bottom surface. The semi-fabricated light scattering film is placed in an oven having a constant temperature and humidity for drying. Check that thickness and physical properties are satisfied. Coating processes such as those described above may be replaced by electrostatic spraying.

Next, anti-ultraviolet ink is printed on the bottom surface of the antistatic adhesive layer 12 in the semi-finished state according to a predetermined layout for forming the optical path adjusting unit 123 composed of a plurality of screen dots.

Finally, the optical film is dried at a temperature of 250 to 500 ° C. in an ultraviolet dryer. The finished product becomes the light scattering film 1 'described in the above-described embodiment.

The light scattering film 1 ′ prepared according to the present invention can directly replace the conventional diffusion sheet (diffusion sheet 1 of FIG. 1), for example, without having to further calibrate the backlight module 1 and FIG. It can be used as a backlight module in various conventional display devices, such as the direct-beam or sub-light backlight module of the conventional LCD device shown in FIG. 6 shows the direct application of the light scattering film 1 ′ of the present invention to a direct light type backlight module equipped with a light source 3. During operation, light emitted from the light source 3 (indicated by a solid line) is directly incident on the antistatic adhesive layer 12, or a part of light emitted from the light source 3 (indicated by a dotted line) is scattered / After being reflected, it is incident on the antistatic adhesive layer 12 and is emitted through the base layer 10 and the diffusion layer 11. Therefore, the final light can obtain a uniform and high luminance. In another exemplary embodiment shown in FIG. 7, the light scattering film 1 ′ of the present invention is directly applied to a sensitized backlight module having a light source 82, the operation of which is similar to that of the embodiment of FIG. 6. Do. FIG. 7 additionally, light partially scattered / reflected through the optical path adjusting unit 123 may be incident on the antistatic adhesive layer 12 after being scattered / reflected on the surface of the supporter 81.

In the actual test, the backlight module of the display device using the light scattering film of the present invention showed uniform brightness, and the brightness was increased even under the condition that the thickness, manufacturing process complexity, and cost did not increase.

While the embodiments of the present invention have been illustrated and described as described above, various modifications and improvements may be made by those skilled in the art. Accordingly, embodiments of the present invention are intended to be illustrative and not limiting. The invention is not limited to the specific forms illustrated, and all embodiments that retain the spirit and scope of the invention are included in the scope defined by the appended claims.

The light scattering film of the present invention as described above has the effects of light reflection, light scattering, light diffusion, condensing, and mixing, and the dark zone is not formed at the position of the liquid crystal panel corresponding to where the light source is located, so that light is uniformly emitted. There is an effect that can increase the brightness.

In addition, the light scattering film of the present invention has an excellent compatibility and there is an effect that can be easily introduced during the conventional manufacturing process without additional manufacturing cost.

On the other hand, the light scattering film of the present invention has light reflecting, light scattering, light diffusing, condensing and converging effects, and thus has excellent outgoing luminance without increasing the volume and cost of the backlight module when applied to the backlight module. The display device manufactured by this method can obtain more excellent output effect.

Claims (8)

A light scattering film used in a backlight module having at least one light source, A base layer having two opposite faces; A diffusion layer formed on one side of the base layer; An antistatic adhesive layer comprising a first surface formed on the other opposite surface of the substrate layer and a second surface having at least one optical path adjustment unit deposited in relation to the arrangement of the at least one light source, The light emitted from the at least one light source is directly incident on the antistatic adhesion layer, or a part of the optical path of the light is adjusted by the at least one optical path adjustment unit to be incident on the antistatic adhesion layer, thereby providing the base layer and the diffusion layer. Light scattering film emitted through. The light scattering film of claim 1, wherein each of the diffusion layer and the antistatic adhesive layer includes a plurality of diffusion particles and an adhesive for fixing the plurality of diffusion particles to the base layer. The light scattering film of claim 2, wherein a weight ratio of the adhesive in the diffusion layer is between 10 and 90 wt%. The light scattering film of claim 1, wherein the base layer has a thickness of 25 μm to 300 μm, the diffusion layer has a thickness of 15 μm to 40 μm, or the antistatic adhesive layer has a thickness of 10 μm to 25 μm. The light scattering film of claim 1, wherein the light path adjusting unit is an opaque material, a partially transparent material, or a translucent material or a combination of these materials. The light scattering film of claim 5, wherein the light path adjusting unit is made of dot-printed anti-ultraviolet ink. The light scattering film of claim 5, wherein the light path adjusting unit has an irregular V shape or an irregular R shape surface. The light source of claim 1, wherein the backlight module is a direct light backlight module, and the light scattering film is positioned vertically above the light source, and a light guide plate is disposed between the light source and the light scattering film to introduce light from the light source into the light scattering film. Light scattering film.

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