KR100650150B1 - Structure of a diffuser with improved transmittance - Google Patents

Abstract

The present invention relates to a diffuser plate structure, wherein an antireflection layer having a low reflectance is formed on a lower surface of the diffuser plate, and the antireflective layer includes a thermosetting resin and a plurality of nano-grade particles. The plurality of nanoscale particles are randomly mixed in the thermosetting resin using ethyl alcohol as a solvent. Since the antireflection layer has a low reflectance characteristic, the transmittance can be improved when the incident light passes through the thin film layer. Moreover, when the incident light passes through the antireflection layer because the antireflection layer includes a plurality of nanoparticles. It is possible to exhibit the effect of light diffusion, thus providing a uniform and high surface light source to the display device.

Diffuser, light distribution module, luminance, thermosetting resin, transmittance, diffusion point, surface light source, nanoparticles

Description

Diffuser plate with improved transmittance {STRUCTURE OF A DIFFUSER WITH IMPROVED TRANSMITTANCE}

1 is a cross-sectional view of a conventional diffuser plate structure.

Figure 2 is a cross-sectional view of the structure of the diffusion plate embodiment with improved transmittance according to the present invention.

Figure 3 is a cross-sectional view of the diffusion plate structure and light distribution module structure with improved transmittance according to the present invention.

<Explanation of symbols for main parts of the drawings>

101: transparent substrate, 103: binder, 105: scattering body. 107: acrylic resin thin film.

201: transparent substrate. 203: main material layer. 205: spherical granules. 207: thermosetting water

G. 209: nanoscale particle. 211: Light guide plate. 213: diffusion point. 215: reflector.

217: incident light. 219: light source

The present invention relates to a diffuser plate, and more particularly, to a diffuser plate with improved transmittance.

A liquid crystal display (LCD) is a display device that cannot emit light by itself and can achieve a display function only by backlight. In the fixed backlight system, the high and low transmittance of the diffusion film can directly affect the effect of using the light source, and thus affect the development quality of the liquid crystal display. Therefore, the diffusion plate is a very important component among the modules of the liquid crystal display. Since high-quality, large-size large liquid crystal displays must be combined with high-performance light distribution technology, high performance of the light distribution technology, for example, high brightness, low cost, low electricity consumption, and light weight, express the overall performance of the liquid crystal display. Plays a very important role.

Light distribution modules in liquid crystal displays generally include a light source (ie, a cold cathode tube), a reflector, a light guide plate, a diffuser plate, and the like. The function of the diffusion plate is to disperse incident light effectively and to provide a uniform surface light source to the liquid crystal display. Conventional diffusion plates include a transparent substrate and a diffusing layer, which are formed on the surface of the transparent substrate. The diffusion layer includes spherical material particles that are scatterers, and the diffusion effect of the diffusion plate is mainly caused by the difference in refractive index between the binder in the diffusion layer and the scatterers included in the binder. The scatterers are dispersed between the diffuser layers, so that when light passes through the diffuser layer, it travels continually between two media with different refractive indices. In this case, the light beam simultaneously causes refraction, reflection, and scattering to achieve an optical diffusion effect.

With the rapid development of flat panel displays, high quality image quality plays an indispensable role. Among them, the brightness representation of a flat panel display is an important part, and the application of an anti-reflection film has become one of the important means in enhancing the luminance representation. The action of the antireflection film is to reduce reflection and increase the light transmittance of the display element, the main principle of which is to use the transmission and reflection characteristics when the incident wavelength passes through the anti-reflective coating layer, a part of the incident wavelength passes through The other part is reflected. The interference effect and the reflection effect are obtained by controlling the value multiplied by the refractive index and the thickness of the reflective coating layer at 1 / 4λ odd times the incident wavelength. As for the liquid crystal display panel, it means that the transmittance of 1% is lost every time the reflectance of 1% is increased. That is, since the luminous intensity of 1% is lost, the liquid crystal display panel should reduce the reflectance while increasing the transmittance as much as possible.

The conventional diffuser plate structure will be described below with reference to FIG. 1. Referring to FIG. 1, a transparent substrate 101 is provided, wherein the material of the transparent substrate 101 is an acrylic resin thin plate, for example, a homogeneous homopolymer, polymethyl methacrylate. ) Can be lamination. A diffusion layer is provided on the transparent substrate 101, and the diffusion layer includes a polymerizable binder 103 and a plurality of spherical scatterers 105. The polymerizable binder 103 uses a polymer polymer containing polyalkyl methacrylate as a main functional group, for example, polyethyl methacrylate or polypropyl methacrylate. The scatterer 105 includes any material having a refractive index, which is different from the refractive indices of the transparent substrate 101, the binder 103, and the acrylate resin thin film 107. The material of the scatterer 105 may be silica, magnesium oxide, titanium oxide, or the like, and the particle size may be 1-100 μm. The polyethylene resin thin film 107 is formed on the diffusion layer and has the same structure as the transparent substrate 101.

When incident light passes through the diffuser layer including the scatterer 105 and the binder 103, the refractive indexes of the scatterer 105 and the binder 103 are different so that phenomena such as refraction, reflection, and scattering occur when the incident light passes. do. That is, the effect that the incident light is diffused can be achieved. However, such a conventional diffuser plate does not have a high light transmittance because only 85% transmittance is achieved since the light transmittance is not high, thus affecting the overall luminance expression of a display element, for example, a liquid crystal display.

Since the transmittance of incident light cannot be improved in using a conventional diffuser, it is urgently required to provide an improved diffuser to improve the transmittance of light and to increase the brightness of a display.

An object of the present invention is to provide an antireflection layer having a low reflectance on the lower side, wherein the antireflection layer provides a diffuser plate capable of increasing the luminance representation of a display by enhancing the transmittance of incident light.

Another object of the present invention is to provide a thermosetting resin comprising nanoparticles, and to use different refractive indices of the nanoparticles and the thermosetting resin, thus providing a uniform surface light source for the display and improving the performance of the light distribution module. It is to provide a diffusion plate.

In order to achieve the above object, the present invention provides a transparent substrate such as a plastic resin substrate in providing an improved diffusion plate. The material may be polycarbonate, polystyrene, polyolefin, polyether, polyester, polyamide, polyphenylene sulfide, polyether-ester, polyvinyl chloride, polymethacrylate and the like. A diffusion layer is formed on an upper surface of the transparent substrate, and the diffusion layer includes a plurality of spherical granules and a host material layer. The plurality of spherical granular materials are organic polymers such as polymethylmethacrylate, or inorganic materials such as titanium dioxide (TiO ₂ ), silicon dioxide (SiO ₂ ) or glass beads, and the main material is also an organic polymer. For example, a urethane resin, a vinyl acetate resin, a vinyl chloride resin, a styrene resin, a polyethylene resin, etc., and at the same time, the diffusion layer may be wedge-shaped or irregular. An anti-reflection layer having a low reflectance is formed below the transparent substrate, and the anti-reflection layer includes a thermosetting resin and a plurality of nano-grade particles. The thermosetting resin and the plurality of nano-grade particles are dispersed using ethyl alcohol as a solvent, randomly mixing the thermosetting resin and the plurality of nano-grade particles by a single manufacturing process such as a wet process or a dry process, and finally the low reflectance An anti-reflection layer having a film is coated or deposited on the lower surface of the transparent substrate.

 EXAMPLE

Hereinafter, the present invention will be described in detail. The descriptions of manufacturing processes and structures in the description below do not include complete flow. Herein, the prior art cited by the present invention is only intended to help explain the present invention by quoting only the points.

The invention is presented below by way of description of a relatively preferred embodiment and associated drawings (FIGS. 2 to 3). Referring to FIG. 2, first, a transparent substrate 201, for example, a plastic substrate, having high transparency and high mechanical strength is provided. The transparent substrate 201 has a thickness of 25 to 150 µm, and the material of the transparent resin substrate 201 made of the plastic resin thin film is polycarbonate, polystyrene, polyester, polyolefin, polyether, polyamide, polyphenylene sulfide, Polyether-esters, or polymethacrylates.

Next, a diffusion layer is formed on the transparent substrate 201, wherein the diffusion layer includes a plurality of spherical granules 205 and the spherical granules 205 are mixed in the main material layer 203. The plurality of spherical granules 205 material is an organic polymer material or an inorganic material, such as polymethylmethacrylate (PMMA), titanium dioxide (TiO ₂ ), silicon dioxide (SiO ₂ ), glass beads, or the like. The material of the main material layer 203 is also an organic polymer material such as urethane resin, vinyl acetate resin, vinyl chloride resin, styrene resin or polyethylene resin. On the other hand, the shape of the diffusion layer formed by including the plurality of spherical granules 205 and the main material layer 203 may have a wedge shape or an irregular shape, wherein the main material layer 203 is fluid. In addition, the diameter of the spherical granules 205 is 1-99 micrometers. Since the refractive index of the individual spherical granules 205 and the refractive index of the main material layer 203 are different, the diffusion of the light beams only occurs when the incident light passes through the interface between the main material layer 203 and the plurality of spherical granules 205. Effect can be achieved.

In the manufacturing method of the diffusion plate, the spherical granules 205 are mixed in the main material layer 203, and then the diffusion layer including the main material layer 203 and the plurality of spherical granules 205 is coated with a transparent substrate 201. Coating on the surface. Next, a curing process is performed to evaporate the organic solvent in the diffusion layer. Among the diffusion layers, the purpose of mixing the plurality of spherical granules 205 in the main material layer 203 is to obtain a plurality of high-density spherical granules 205, and the incident light is emitted by the high-density spherical granules 205. It can spread evenly when passing through. However, the weight of the spherical granules 205 should not exceed 300% of the weight of the main material layer 203. When it exceeds 300% of the weight of the main material layer, the incident light cannot obtain an appropriate transmittance and also affect the adhesiveness of the resin. On the other hand, the weight of the spherical granules 205 should be at least 10% of the weight of the main material layer 203. If less than 10% of the weight of the main material layer affects the diffusion effect of the incident light. Therefore, the density of the spherical granules 205 mixed in the main material layer 203 should be properly controlled.

The diffuser plate formed of the spherical granules 205 and the main material layer 203 can achieve the effect of transmitting incident light, but its transmittance is limited. For example, only 85% light transmittance can be achieved. For this reason, the present invention forms an anti-reflection layer having a low reflectivity on the lower surface of the transparent substrate 201, wherein the antireflection layer includes a plurality of nano-grade particles 209 and a thermosetting resin 207. ). The plurality of nanoparticles 209 are randomly mixed in the thermosetting resin 207, and both are mixed in an ethyl alcohol solvent. The thickness of the antireflection layer is in the range of 1 to 30 μm, and the diameter of the plurality of nanoparticles is in the range of 0.001 to 0.1 μm. When incident light passes through the antireflection layer formed by including the plurality of nanoparticles 209 and the thermosetting resin 207, the incident light simultaneously transmits and reflects. According to the present invention, since the antireflection layer including the plurality of nanoparticles 209 and the thermosetting resin 207 is formed and the antireflection layer has a low reflectance, the reflectance of incident light can be reduced and the transmittance of the incident light can be improved. For example, the light transmittance of 5% can be improved. In addition, since the anti-reflection layer includes a plurality of nanoparticles 209, the diffusion effect of the incident light beams can be increased when the incident light beams pass through the thin film layer, so that the display, for example, a liquid crystal display, has a uniform brightness. Provides a high surface light source.

In addition, the anti-reflection layer including the plurality of nanoparticles 209 and the thermosetting resin 207 forms the anti-reflection layer on the lower surface of the transparent substrate 201 using one manufacturing process, for example, a wet process. . The wet process uses a coating method or an ultra-thin coating method, for example, a micro-gravure coating method, a web tension coating method, and an anti-reflection layer on the lower surface of the transparent substrate 201. After coating, a curing process is performed to remove the ethyl alcohol solvent in the anti-reflection layer. In addition, during the dry process, the thermosetting resin 207 and the plurality of nanoparticles 209 are mixed with an ethyl alcohol solvent, and then the antireflective layer having the low reflectivity using the vapor deposition method, for example, a vacuum deposition method, is formed on the transparent substrate. It deposits on the lower surface of 201. Since the thickness of the antireflection layer can be precisely controlled by the deposition method, the reflectance can be controlled in the range of 0.1% to 2.5% within all visible light ranges (400 to 700 nm). This completes the structure of the diffusion plate according to the present invention.

According to the actual measurement result, the low reflectivity antireflection layer described in the present invention can increase the transmittance of incident light by about 5%. Therefore, by manufacturing a diffusion plate having a high transmittance using the antireflection layer having the low reflectance and applying the structure to the light distribution module, it is possible to compensate for the intensity of light that is lost in incident light passing through the light distribution module. As shown in FIG. 3, a light distribution module may be provided, wherein the light distribution module may include a light source 219, and the light source 219 may provide parallel incident light rays 217. In addition, the light distribution module provides a light guide plate 211 on a lower surface of the low reflectivity anti-reflection layer, the material of the light guide plate 211 may be an acrylic resin, and the light guide plate 211 may be spaced at the same interval on the bottom surface thereof. A plurality of spaced apart diffusion points 213 are included. The material of the diffusion point 213 may be titanium dioxide (TiO ₂ ). On the other hand, the light distribution module increases the use efficiency of the incident light 217 by providing a reflecting plate 215 on the lower surface of the light guide plate 211. When the diffusion plate according to the present invention is installed in the light distribution module, it is possible to provide a light distribution technology of high performance in a display, for example, a liquid crystal display, by the high transmittance characteristic of the diffusion plate.

As can be seen through the specific embodiment according to the present invention, one of the advantages of the present invention is to provide a diffusion plate structure as follows. That is, a low reflectance antireflection layer is formed on the lower surface of the diffusion plate structure, the antireflection layer is a thermosetting resin and includes a plurality of nano-grade particles, and the plurality of nano-grade particles are ethyl alcohol as the solvent and the thermosetting resin. Are randomly mixed. Since the antireflection layer has a low reflectance characteristic, the transmittance can be improved when the incident light passes through the thin film layer. Furthermore, since the antireflection layer includes a plurality of nanoparticles, the incident light diffuses when passing through the antireflection layer. It is possible to achieve a uniform and high luminance surface light source for the display.

The foregoing is only a comparatively preferred embodiment of the present invention, which does not limit the claims of the present invention. At the same time, the above description is obvious to the person skilled in the art and can be carried out without departing from the scope of the present invention, and any equivalent changes, additions, or modifications that have been made will be included in the claims of the present invention. .

Claims (5)

A plastic resin substrate, a diffusion layer, and an antireflection layer, The diffusion layer is provided on the upper surface of the plastic resin substrate, and is composed of a main material layer and a plurality of spherical granules, The anti-reflection layer capable of increasing light transmittance is provided on a lower surface of the plastic resin substrate, and the thermosetting resin and the plurality of nanoparticles are formed by mixing ethyl alcohol as a solvent. Diffuser plate structure in light distribution module. The method of claim 1, The plastic resin substrate material is selected from polycarbonate, polystyrene, polyester, polyolefin, polyether, polyamide, polyphenylene sulfide, polyether-ester, polyester and polymethacrylate The diffusion plate structure in the light distribution module. The method of claim 1, And the main material layer material is selected from urethane resin, vinyl acetate resin, vinyl chloride resin, styrene resin and polyethylene resin. The method of claim 1, The diameter of each of the plurality of spherical granules is in the range of 1 to 99 μm, the weight ratio of the plurality of spherical granules to the main material layer is in the range of 3 to 0.1, and the plurality of spherical granular materials is polymethyl methacrylate (PMMA). And titanium dioxide (TiO ₂ ) and silicon dioxide (SiO ₂ ). The method of claim 1, The thickness of the antireflection layer is in the range of 1 to 30 μm, the diameter of the plurality of nanoparticles is in the range of 0.001 to 0.1 μm, and the reflectance of the antireflection layer is controlled to be 0.1% to 2.5% within the visible light range (400 to 700 nm). Diffusion plate structure in the light distribution module, characterized in that.

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