KR100371393B1 - Manufacturing Method of Optical Sheet and Optical Sheet for Liquid Crystal Displays - Google Patents

Abstract

PURPOSE: An optical sheet for liquid crystal display panel and a method for fabricating the optical sheet are provided to simplify a liquid crystal display panel assembling process and produce a thin liquid crystal display panel. CONSTITUTION: An optical sheet of a liquid crystal display panel includes a light transmission base sheet(12), a light-condensing lens(11), and a light diffusion layer(15). The light-condensing lens is formed on one side of the base sheet and consists of a fine triangular prism, a spherical or aspherical lens and a fresnel lens. The light-condensing lens has a strip form. Lights input to the optical sheet are condensed within a predetermined angle while passing through the light-condensing lens. The lights are diffused in the light diffusion layer due to a refractive index difference between a binder resin(13) and a diffusion fine grains(14) of the light diffusion layer, to thereby make the brightness of the front side of the optical sheet uniform.

Description

Optical Sheet for Liquid Crystal Display Panel and Manufacturing Method Thereof {Manufacturing Method of Optical Sheet and Optical Sheet for Liquid Crystal Displays}

The present invention relates to an optical sheet for a liquid crystal display panel and a method of manufacturing the same.

The liquid crystal display panel is an image display device widely used in game machines, office equipment, portable computers, etc., and since the liquid crystal itself does not have a light emitting ability, a rear adjustment device is used as a light source.

In the case of the color liquid crystal display panel, the transmittance of light is lower than that of the monochromatic liquid crystal display panel, so that a rear illumination device having a luminance higher than that required in the back lighting apparatus used in the monochromatic liquid crystal display panel is required.

In order to manufacture a high brightness rear lighting device, it is necessary to increase the capacity of the fluorescent lamp or increase the number of lamps used. However, since the power consumption is increased, the use time of the battery is short and the volume is large. .

Due to the limitations of this technology, in order to increase the brightness, the conventional technology includes a prism sheet, a spherical or aspheric lens, and a Fresnel lens sheet having a function of condensing light diffused on a light diffusion sheet on a light guide plate. 6-194651, 6-265888) and the like were used to condense the light within a certain angle to improve the brightness.

However, in the conventional method, many types of sheets, such as a light diffusion sheet and a light collecting sheet, are inserted between the light guide plate and the liquid crystal display panel (LCD), and light is absorbed by the sheet while the light passes through the sheet. It is lowered, and a lot of defects are caused by stacking and combining many kinds of many sheets even in the manufacturing process, and there is a problem such as reversing the development of thin liquid crystal display device required by the consumer due to the increase in the thickness of the sheet.

Accordingly, the inventors of the present invention have repeatedly studied to solve the above problems. As a result, the assembly process is simplified, thereby reducing assembly defects and the number of assembly processes. It came to invent the sheet | seat for.

1A is a perspective view of an optical sheet of the present invention, and FIG. 1B is a cross-sectional view of the optical sheet of the present invention.

2 is a cross-sectional view of the sheet for collecting light.

3 is a cross-sectional view of a sheet for light diffusion.

4 is a cross-sectional view of a back light unit for a liquid crystal display panel of the prior art.

Fig. 5 is a cross sectional view of a rear lighting apparatus using the product of the present invention.

6 is a front view of a manufacturing apparatus for producing the sheet of the present invention.

〈Description of the symbols for the main parts of the drawings〉

1: condensing sheet

2: light diffusion sheet

3: light guide plate

4: reflection shade

5: fluorescent lamp

6: reflective pattern

7: liquid crystal display panel

11: condensing lens unit

11a: triangular prism

11b: Spherical or Aspheric Lens

11c: Fresnel lens

12: transparent transparent base sheet

13: binder resin

14: fine particle for light diffusion

15: light diffusion layer

21a: guide roller

21b: pressure roller

21c: Release Roller

22: ultraviolet irradiation device

23a, 23b: coating device

24: embossing roller

The present invention is an optical sheet that is applied to the back lighting device of the liquid crystal display panel (LCD), and more specifically, after the UV curable resin is applied to the emboss roller having a series of fine triangular prism shape using a guide roller using a light transmissive substrate sheet After pressurizing with UV light to irradiate the light transmissive substrate to produce a prism sheet having a series of fine triangular prism shape, and then the light diffusing particles and UV curable binder resin having a light diffusing function on the opposite side of the light transmissive substrate sheet It relates to an optical sheet obtained by irradiating ultraviolet rays after coating to a certain thickness in combination. In addition, the present invention is applied to the back lighting device of the liquid crystal display panel (LCD) by uniformly dispersing the uneven surface light irradiated from the light guide plate on the surface with the light diffusion layer, and then scattered light at a constant angle, that is, about 70 The present invention relates to an optical sheet having a property of condensing at -130 ° to improve luminance by 50% or more and improving luminance uniformity of surface to 85% or more, a liquid crystal display panel including the same, and a manufacturing method.

In order to achieve the object of the present invention as described above, the optical sheet of the present invention is a UV curable resin on an embossed roller carved in the shape of a prism, spherical or aspherical lens, Fresnel lens, etc., which may have a condensing function. After coating, the light-transmitting base sheet is pressed to the emboss roller by a pressure roller to form a shape having a light condensing function, and then irradiated with ultraviolet light to the light-transmitting sheet surface to cure the resin, followed by release to make a light-condensing sheet. The resin sheet, which is used as a binder, and the light diffusing fine particles are mixed together on the sheet surface on the other side of the sheet having the condensing function based on the sheet thus formed, coated to a predetermined thickness, and then irradiated with ultraviolet rays to produce a curing process. .

Hereinafter, a product and a manufacturing apparatus according to the present invention will be described in detail with reference to the accompanying example drawings.

As shown in FIGS. 1A and 1B, the optical sheet according to the present invention has a fine triangular prism 11a, a spherical or aspherical lens 11b, a Fresnel designed to have a light condensing function on one side of the light transmissive substrate sheet 12. The lens 11c is arranged to form a series of continuous elongated shapes so that light passes and is condensed within a certain range of angles. The opposite side having the light condensing function is a light diffusing layer 15 so that the incident light is used for light diffusion. While passing through the microparticles | fine-particles 14, it spreads by the refractive index difference of the binder resin 13 and the microparticles | fine-particles for diffusion 14, and has a function which makes the brightness of the whole surface of a sheet uniform.

As the binder resin 13 of the light collecting lens parts 11a, 11b, 11c and the light diffusion layer 15 of the present invention, a self-curing resin composition can be used. It is preferable to use the resin composition which can form the crosslinked bonded to shape retention. UV or electron beam curable resin composition suitable for such use can be epoxy resin-ruic acid type, polyethylol type, unsaturated polyester-styrene type, acrylic or methacrylic acid ester type, etc. Or it is effective to use methacrylic acid ester resin.

Such resins include oligomers such as polyurethane acrylics or methacrylates, epoxy acrylics or methacrylates, polyester acrylics or methacrylates and are either alone or diluted with acrylic or methacrylate monomers having poly or monofunctional groups. It is preferable to use. Ultraviolet rays or electron beams can be used as the method for curing the resin composition of the present invention. However, in consideration of facility investment cost, curing rate, etc., it is economical to use an ultraviolet curing method.

The shape of the condenser lens portion may be a triangular prism 11a, a spherical or aspherical lens 11b, a Fresnel lens 11c, or the like. The triangular prism shape 11a has excellent light condensation, but has low wide viewing angle characteristic, which is sensitive to the change of brightness according to the angle of looking at the liquid crystal display panel, and the spherical or aspherical lens shape 11b has excellent wide viewing angle characteristic but It is disadvantageous in that it is disadvantageous in improving luminance and has a disadvantage in that the manufacturing method is difficult. In view of the fact that the main purpose of using the optical sheet is the increase in luminance, it is preferable to have a triangular prism shape as the shape of the condensing lens portion.

The triangular prism 11a is severely changed in brightness and wide viewing angle depending on the vertex angle α of the prism. As the vertex angle α is increased, the wide viewing angle is good, but the luminance increase is disadvantageous, and when the vertex angle α is smaller, the opposite phenomenon occurs. As for the vertex angle ( alpha ) of the triangular prism 11a, 80-100 degrees are preferable. When the vertex angle α of the triangular prism 11a is 80 ° or less, the luminance due to condensation is good, but the light viewing angle is poor, so that it is difficult to apply. When the angle is greater than 100 °, the wide viewing angle characteristic is good but the brightness is low. In view of this point, it is particularly preferable to use the angle of the vertex α in the range of 85 to 95 °.

The pitch w of the condensing lens portion of the optical sheet may be used to be 75 to 80 μm or less, which is generally identifiable by the naked eye at a distance of about 250 mm from the liquid crystal display panel, but the color of the thin film transistor (TFT) or the like may be used. In order to remove the moire generated on the screen by the pitch between the color filter used to implement and the pitch between the optical sheet, it is preferable to set the pitch (w) size between 20 and 50 μm .

Materials that can be used as the light transmissive transparent substrate 12 include polyvinyl chloride sheet, polycarbonate sheet, polymethyl methacrylate sheet, polyester sheet, and the like, and mechanical properties, light transmittance, mass production, and environment for use of the optical sheet. In consideration of conditions, polyester films are often used.

As light passes through the medium, part of it is absorbed by the medium, so that the thickness of the optical sheet should be as thin as possible to maintain the shape of the product in order to minimize the absorption of light into the medium and maintain the brightness. desirable. When selecting a polyester of a light transmissive base material for use in the present invention, the products that the tensile strength of the sheet 15 Kg / mm ² or more, and light transmittance of 90% or more the thickness is to use the product of 80~200 μ m range effective.

The raw material for forming the light diffusing layer 15 is composed of light diffusing fine particles 14 for diffusing light and a binder resin 13. The binder resin 13 is made of the same material as the resin used in the condensing lens unit 11. It is preferable to consider the optical properties and the like that is used.

As the light diffusing fine particles 14, fine particles made of inorganic materials such as glass, talc, aluminum oxide, titanium dioxide, and organic materials such as polystyrene, polycarbonate, and PMMA can be used. Particles such as talc, aluminum oxide, and titanium dioxide do not transmit light, but reflect from the surface to diffuse light. Particles such as glass, polystyrene, polycarbonate, and PMMA transmit and refract the incoming light, thereby causing light paths. It has the function of diffusing light by changing it. In order to improve the function of the light diffusing layer 15 such as the light diffusing effect and the light transmittance, it is effective to use fine particles such as glass, polystyrene, polycarbonate, PMMA, etc. having a function of transmitting and refracting light.

The size of the light diffusing fine particles 14 is effective in improving light transmittance and light diffusing efficiency by using a product having a sphere formation in the range of 2 to 30 μm , and the size of the fine particles rather than using similarly sized fine particles alone. It is preferable to use divided into two or more. When the light diffusing fine particles 14 having similar sizes are used alone, the ratio of incoming light does not pass through the light diffusing fine particles 14 but passes between the optical diffusing fine particles 14 is high, thus obtaining a uniform surface light source. If the coating is thick to block light passing between the particles, the light diffusion effect is high but the light transmission efficiency is low. When two or more sizes of the light diffusing fine particles 14 are selected and used, small particles are distributed between the large particles and the fine particles, and the light passing through the large particles can be transmitted and refracted by the small particles to reduce the coating thickness. The light transmission efficiency can be increased, and at the same time, the light diffusion function can be improved to obtain a uniform light source.

A method of making the product of the invention described above is shown in FIG. 6. As shown, the base sheet 12 is pressed against the embossing roller 24 using the coating apparatus 23a of the method suitable for the embossing roller 24 which has the shape of the condensing lens 11. As shown in FIG. In this pressurized state, ultraviolet rays are irradiated onto the transparent substrate sheet 12 for light transmission to cure and solidify the resin composition, and then release from the embossing roller 24 on the release roller 21c to make a light collecting lens, and then to collect light lenses. The light diffusing fine particles 14 are mixed with the binder resin 13 on the surface of the sheet of light transmitting substrate 12 opposite to the condenser lens forming portion 11a of the sheet, and uniformly using a suitable coater 23. After coating with a thickness, ultraviolet light is irradiated with the ultraviolet irradiation device 22 to produce an optical sheet having both a light diffusing function and a light condensing function.

The manufactured optical sheet not only reduces the number of parts compared to the existing products, but also eliminates the gap between the sheets and the thickness of the sheets so that the light transmittance can be increased, thereby improving the luminance and reducing the thickness of the product. Has

Claims (11)

In the optical sheet for the back lighting device of the liquid crystal display panel, a) a light transmissive substrate; b) a condensing lens portion in contact with one side of the substrate and having a plurality of lenses made of an ultraviolet curable resin; And c) An optical sheet comprising a light diffusing layer made of a provider resin in which light-diffusing fine particles having two or more kinds of particle sizes are in contact with the other side of the substrate. The optical sheet of claim 1, wherein the lens has a triangular prism, spherical surface, aspherical surface, or freesnel shape. The optical sheet according to claim 2, wherein the lens shape is a triangular prism. The optical sheet according to claim 3, wherein the vertex angle of the triangular prism is in the range of 85 to 95 degrees. The optical sheet of claim 3, wherein the distance between the vertices of the triangular prism is in the range of 20-50 μm . The optical sheet of claim 1, wherein the light transmissive substrate is made of polyvinyl chloride, polycarbonate, poly methyl methacrylate, or polyester resin. The optical sheet of claim 1, wherein the light diffusing fine particles are made of glass, polystyrene, polycarbonate, polymethyl methacrylate. The method of claim 7, wherein the optical sheet, the size of the light diffusing fine particles 2~30 μ m. In the optical sheet for the back lighting device of the liquid crystal display panel, a) a light transmissive substrate; b) a condensing lens portion in which a triangular prism shape lens having a vertex angle of 85 to 95 ° is arranged at an interval of 20 to 50 μm on one side of the substrate; And c) An optical sheet comprising a light diffusing layer made of a binder resin embedded with particles for refracting incoming light having two or more different particle sizes of 2 to 30 μm on the other side of the substrate. In manufacturing the optical sheet for the back lighting device of the liquid crystal display panel, a) coating an ultraviolet curable resin composition on the embossing roller in which the condensing lens shape is carved; b) pressing the transparent transparent substrate with a pressure roller; c) irradiating ultraviolet rays to produce a light collecting lens; d) coating the binder resin mixed with the light diffusing fine particles on the opposite side; And e) irradiating ultraviolet light Method for producing an optical sheet comprising a. In a liquid crystal display device comprising a light guide plate, an optical sheet, and a liquid crystal display panel, the optical acid sheet is a) a light transmissive substrate; b) a condensing lens portion in contact with one side of the substrate and having a plurality of triangular prism, spherical, aspherical or Fresnel-shaped lenses made of an ultraviolet curable resin; And and c) a light diffusing layer made of a provider resin in which light-diffusing fine particles having two or more kinds of particle sizes are in contact with the other side of the base material.

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