KR101175749B1 - Optical film enhanced brightness and diffusion - Google Patents

Abstract

The present invention relates to an optical film having improved brightness and diffusivity, and more particularly, to a base layer; And it provides an optical film with improved brightness and diffusivity, characterized in that the ring-shaped and irregularities are formed on the upper surface of the base layer.

Description

Optical film enhanced brightness and diffusion}

The present invention relates to an optical film for improving brightness and diffusivity, and more particularly, to an optical film having improved brightness and diffusivity applied by forming a pattern with respect to an optical film for a backlight unit.

Recently, various flat panel display devices have been developed. These flat panel display devices include liquid crystal displays (LCDs), plasma display panels (PDPs), and field emission displays (FEDs). In addition, studies are being actively conducted to improve the display quality of such flat panel displays.

Among them, LCD is a device that injects liquid crystal between two sheets of glass and applies power to the electrodes installed on the upper and lower glass plates to change the arrangement of liquid crystal molecules and display images in each pixel. Such an LCD display device generally comprises an LCD panel unit, a driving unit, and a backlight unit. The LCD panel has a structure that can not emit light itself and has merely a function of transmitting light on the rear surface. Therefore, in the absence of light, that is, at night or indoors, it is a structure that can not display images without the help of backlight. The backlight unit refers to a system for implementing the backlight of such an LCD.

Backlight units consist largely of lamps, sheets, mechanisms, and drive circuits. Since the lamp alone can not produce uniform light over the entire area, it is provided with sheets and mechanisms such as a light guide plate, a diffusion plate, a reflection plate, a prism, and a frame.

There are various methods for the backlight unit, and the most widely used method is a cold cathode fluorescent lamp (CCFT) having a light guiding plate (LGP) printed with a reflection pattern in the center by side light method. The cold cathode fluorescent lamp is placed on the edge. At this time, the reflective pattern printed on the light guide plate is printed in a structure to reduce the phenomenon that the brightness difference occurs depending on the position of the lamp is located at the edge of the panel. Although the method of printing the reflective pattern on the light guide plate is high in productivity, the light loss caused by the printing pattern material itself is inferior in efficiency, and the larger the LCD, the worse the uniformity of the overall brightness.

Since the light guide plate method does not provide sufficient brightness, a direct method in which a plurality of lamps are arranged at regular intervals under the diffuser plate is used. In this method, several fluorescent lamps are arranged in a row on the rear surface of the diffusion sheet to improve luminance and improve uniformity than the photometric type. In order to display a bright screen, the backlight light source must be very bright. This is because the light from the light source goes through several steps before reaching the LCD, and loses its original brightness in the process. In addition, the uniformity of light throughout the screen is lost because of the scattering effect.

One way to overcome this problem is to increase the size of the light source, but this is expensive installation cost, high power consumption, and also has a problem of increasing the weight a lot. Thus, several attempts have been made to improve the light source brightness without loss as much as possible during the transmission process.

In flat panel display devices such as LCDs and projection TVs, a diffuser is an optical element that plays an important role in reaching light from the light source to the viewer's eyes. The diffuser plate uniformly distributes the light from the light source and plays an important role in the direct type than in the case of LCD. Structural metering is a structure where light guided by a light guide can be uniformly distributed throughout the screen, but in the case of a direct type, several light sources are distributed below the screen, so that the point just above the light source and the point between the light source and the light source Because there is a difference in the light intensity, you have to offset it.

The most important optical properties of the optical film used to improve visibility in the backlight unit are light transmittance and haze, which require a total amount of light of 60% or more and 85% or more of light for visible light. In order to satisfy these characteristics, a light diffusing film generally has a surface diffusion method of refraction or dispersion in a number of directions using irregularities of the surface and a bulk diffusion film method having an inherent light dispersion element.

The surface diffusion type diffusion film uses a rough surface exposed to air to maximize the difference in refractive index between the material of the diffusion film and the surrounding medium as much as possible to spread the incident light at the largest angle. For example, light diffusivity is imparted by forming irregularities on the film surface. There is a light diffusing film in which the unevenness is formed on the surface of the transparent resin made of a polyester resin, a polymethyl methacrylate resin or a polycarbonate resin. However, it is difficult to simultaneously obtain excellent light transmittance and light diffusivity only by imparting irregularities to the surface by embossing or sand blasting. In addition, the temperature in the backlight unit generally rises from 80 ° C to 90 ° C, and when the humidity is high, shape deformation may occur severely, so that a material having excellent optical properties while having high heat resistance and low moisture absorption rate is used.

The bulk diffusion film is a light diffusing agent such as fine particles dispersed within the film, and is usually made of a transparent resin made of a resin such as polymethyl methacrylate, polycarbonate, etc., calcium carbonate, titanium dioxide, glass beads, silica particles, polystyrene There are light diffusing films in which particles, silicone resin particles, crosslinked polymer particles and the like are dispersed.

Korean Unexamined Patent Publication No. 2007-0078293 discloses a light collecting member, a method of manufacturing the same, and a display device having the same. The light collecting member includes a base layer, a light collecting layer, and a lower surface treatment layer. The light collecting layer is formed on the upper surface of the base layer and has a light collecting pattern. The lower surface treatment layer is formed on the lower surface of the base layer and consists of round protrusions. The protrusion has a height-to-width ratio in the range of about 0.01 to 0.06, which reduces manufacturing costs by using only one light collecting member, and improves display quality by preventing scratches and adhesion with the diffuser plate. There is an advantage. However, the patent has an advantage of improving scratch resistance and diffusivity, but there is a problem that the brightness is lowered.

Due to the above problems, it is desired to develop an optical film that can improve the diffusivity and at the same time improve the luminance.

In order to solve the above problems, an object of the present invention is to provide an optical film having excellent brightness and excellent diffusibility in performing a role as an optical film.

Another object of the present invention is to provide an optical film having excellent scratch resistance and improved physical properties as an optical film such as haze.

The present invention to solve the above problems is a base layer; And it provides an optical film with improved brightness and diffusivity, characterized in that the ring-shaped and irregularities are formed on the upper surface of the base layer.

In another aspect, the present invention provides an optical film with improved brightness and diffusivity, characterized in that the irregularities are formed both inside and outside the round annular shape of the upper surface of the base layer.

In another aspect, the present invention provides an optical film with improved brightness and diffusivity, characterized in that irregularities are formed on the lower surface of the base layer.

In another aspect, the present invention provides an optical film with improved brightness and diffusivity, characterized in that the thickness of the base layer is 150 to 800㎛.

In another aspect, the present invention provides an optical film with improved brightness and diffusivity, characterized in that the outer ring is 50 to 180㎛, the inner diameter is 30 to 150㎛.

In another aspect, the present invention provides an optical film with improved brightness and diffusivity, characterized in that the round ring-shaped height is 10 to 50㎛.

In another aspect, the present invention provides an optical film with improved brightness and diffusivity, characterized in that the round annular spacing is 30 to 300㎛.

In another aspect, the present invention provides an optical film with improved brightness and diffusivity, characterized in that the irregularities provided on the upper or lower surface of the base layer has a Rz value of 5 to 10㎛, Ra value of 1 to 2㎛.

In the present invention, the base layer is methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydride Monomer selected from oxypropyl methacrylate, hydroxyethyl acrylate, acrylamide, metalolacrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate and 2-ethylhexyl acrylate Improved brightness and diffusivity further comprising one or more selected light diffusing particles consisting of beads and silicon-based spherical particles made of homopolymers, copolymers or terpolymers, polyethylene, polystyrene, polypropylene, acrylic and olefin copolymers Provide an optical film.

Optical film according to the present invention has the effect that can be implemented at the same time to improve the brightness and diffusion.

In addition, the optical film according to the present invention has an effect of providing an optical film having excellent scratch resistance while improving physical properties as an optical film such as haze.

1 shows a perspective view of an optical film according to an embodiment of the present invention.
2 shows a cross-sectional view of an optical film according to an embodiment of the present invention.
Figure 3 shows a schematic view of a round ring-shaped according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that, in the drawings, the same components or parts have the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

The terms " about ", " substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation to or in the numerical value of the manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

As used herein, the term "film" is used to mean both films, sheets, and plates having a predetermined width and thickness.

The present invention relates to an optical film with improved brightness and diffusivity, the base layer; And a round ring shape and irregularities are formed on an upper surface of the base layer.

1 and 2 show a perspective view and a cross-sectional view of an optical film according to an embodiment of the present invention. In addition, Figure 3 shows a round ring shape included in the upper surface of the base layer in one embodiment of the present invention.

Referring to Figures 1 and 2, the present invention consists of a round ring-shaped pattern for improving the brightness on the film upper surface consisting of a base layer. The base layer is preferably formed of a transparent resin material, and non-limiting examples of the resin include polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), and polypropylene terephthalate (PPT). , Polynaphthalene terephthalate (PEN), polyethylene terephthalate glycerol (PETG), polycyclohexylenedimethylene terephthalate (PCTG), polyethersulfone (PES), polymethyl methacrylate (PMMA), polyimide (PI) 1 or 2 or more selected from the group consisting of polyarylate (PAR) and silicone resin may be blended resin. In addition, the thickness of the base layer is preferably 150 to 800㎛.

The upper surface of the base layer forms a round annular shape and unevenness, the round annular shape serves to improve the brightness by condensing the traveling direction of light.

Light incident through the base layer may serve to condense or reflect by the round annular shape. This has the advantage that the luminance is improved compared to other shapes such as a round ring-like lens shape.

Referring to Figure 3, it shows a round annular shape included in the upper surface of the base layer, while improving the adhesion with other films stacked on top of the optical film according to the present invention to minimize the loss of incident light to improve the brightness It is preferable that it is formed by what can be. That is, the upper surface of the ground layer is formed in a round ring shape, thereby minimizing distortion of incident light and improving luminance.

In addition, the optical film according to the present invention is preferably formed with irregularities on the upper surface of the ground layer. As the concave-convex is formed together with the round ring shape, the scattering effect of the light can be enhanced, which is effective in improving the diffusibility and can prevent scratches.

That is, in the optical film of the present invention, a round ring shape and irregularities are formed on the upper surface of the base layer, thereby improving luminance and improving diffusibility.

In addition, it is possible to form irregularities on the lower surface of the base layer, which is to prevent scratches of the optical film.

Surface roughness of uneven | corrugated surface can be given to the upper surface and lower surface of a base layer so that Rz value may be 4-10 micrometers, and Ra value may be 1-2 micrometer. It is excellent in the diffusivity within the above range, there is an effect to reduce the defects due to stains, etc. generated during processing, and to reduce the occurrence of scratches in the process and moving means.

The round annular shape of the upper surface of the base layer may be represented by an outer diameter and an inner diameter. The outer annular outer diameter of the round annular shape is preferably 50 to 150 µm and the inner diameter is 30 to 120 m. In addition, when the height of the round annular shape is to increase the length from the base layer surface to the highest position of the round annular shape, the height of the round annular shape is preferably 10 to 50 µm. When the diameter and height of the round annular shape are within the range, light distortion is minimized and light is well collected.

The round annular shape is preferably arranged in uniform contact with a plurality of the same size. In addition, the round annular spacing is preferably 30 to 300 µm.

Meanwhile, the base layer may further include light diffusing particles for the diffusion effect. Since the light diffusing particles should be compatible with a binder (resin) containing particles, organic particles having a similar refractive index to materials and spheres having a low refractive index The silicon particles were examined and used, and inorganic particles having a refractive index of 1.50-1.80 can be used. Particularly, the particle selection to be used is advantageous for solving the problem such as showing the bright line due to the spherical particles having the refractive index difference of 0.1 to 0.2 from the material to improve the shielding, and to maximize the diffusion effect with a relatively small particle amount. It is very advantageous.

The refractive index of the diffusing agent particles used increases the light diffusion effect as the difference between the material and the refractive index is larger, but when the refractive index difference is too large, it is disadvantageous in terms of increasing the brightness, so that the proper refractive index difference is obtained and sometimes similar to the material. It is preferable to use the particle | grains with a big difference.

Non-limiting examples of light diffusing particles that can be used in the present invention include methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, Hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, acrylamide, metalolacrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate and 2 Homopolymers, copolymers or terpolymers of monomers selected from ethylhexyl acrylate, beads made from copolymers of polyethylene, polystyrene, polypropylene, acrylics and olefins, and silicone-based spherical particles may be used. Preferably, the material is spherical particles between 1 μm and 10 μm having a refractive index difference of about 0.1 to about 0.2. Spherical organic particles having such a difference in refractive index can be easily dispersed in the resin because they have densities similar to those of the material used in the present invention (about 1.10 to 1.30 g / cm 3).

The light diffusing particles used in the present invention may use different ones in type and / or size. For example, light diffusion efficiency can be enhanced by mixing two or more kinds of particles having a difference in refractive index rather than a single type. In addition, light diffusing efficiency may be increased by using particles having similar refractive indices and different sizes, and by applying porous particles, the brightness may be increased while maximizing light diffusing efficiency after assembling the backlight unit.

Using particles of uniform particle size requires a large amount of particles to produce a predetermined light diffusing effect, which results in not only economic inefficiency, but also lowering the overall light transmittance. According to one embodiment of the present invention, the size of the light diffusing particles can be used to increase the light diffusion effect while reducing the particle content by using two kinds of particles having a size of 20 to 30 ㎛ and 1 to 15 ㎛.

The light diffusing particles may be used at 0.5 to 20% by weight, preferably 1 to 10% by weight based on the total weight of the optical film. When the light diffusing particles are 0.5 wt% or less, a predetermined light diffusing effect cannot be obtained, and when the light diffusing particles is more than 20 wt%, the light transmittance is lowered, and the dispersibility of the particles is reduced and uniform. Particle dispersion cannot be obtained.

Hereinafter, embodiments of the present invention will be described in detail.

Example  One

The optical film is manufactured using polycarbonate as a polymer resin. The base layer has a thickness of 300 μm, and a round ring shape is given to the upper surface of the base layer, but the outer diameter is 100 μm, the inner diameter is 60 μm, and the height is 25. A micrometer was formed, and the round annular spacing was about 30 to 300 μm, and irregularities were formed on the upper surface of the base layer.

Example  2

The same procedure as in Example 1 was carried out, but the outer ring was 180 μm in diameter, the inside diameter was 140 μm, and the height was 30 μm to form an optical film.

Example  3

In the same manner as in Example 1, but the thickness of the base layer to be 400㎛, to give a round ring shape on the upper surface of the base layer, the outer diameter is 150㎛, the inner diameter is 120㎛, the height is formed to 25㎛, Concave and convexity was formed on the upper and lower surface of the base layer, but the Rz value was 5 μm and the average Ra value was 1 μm to prepare an optical film.

Example  4

In the same manner as in Example 1, but was mixed with 1 part by weight of ethyl methacrylate as a light diffusing agent to 100 parts by weight of the resin of the base layer was blended to prepare an optical film.

Comparative example  One

The optical film is manufactured using PET as the polymer resin, and the thickness of the base layer is 300 μm, and the top surface of the base layer is formed in the shape of a lens, but the diameter is

Comparative example  2

In the same manner as in Example 1, an optical film was prepared without forming irregularities.

* Test Methods

1. Transmittance (TT) and haze (Haze): Measured by ASTM D1003 method using NIPPON DENSHOKU 300A analyzer.

2. Luminance: Measured on a stage equipped with a film produced in the backlight unit, TOPCON BM-7 with CCFL voltage of 16.5V, Dimming value 2.8V.

Table 1 shows the results of testing optical characteristics such as transmittance for each of Examples and Comparative Examples.

division Transmittance (%) Haze (%) Brightness (cd / m 2) Example 1 69 91.8 10230 Example 2 66 91.5 10200 Example 3 67 91.4 10180 Example 4 68 91.0 10120 Comparative Example 1 66 90.3 9800 Comparative Example 2 67 89.5 9920

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be clear to those who have knowledge of.

Claims (9)

Base layer; And
The optical film with improved brightness and diffusivity, characterized in that the ring-shaped and irregularities are formed on the upper surface of the base layer. The method of claim 1,
The irregularities are optical film with improved brightness and diffusion, characterized in that formed on both the inside and the outside of the round annular shape of the upper surface of the base layer. The method of claim 1,
Unevenness is formed on the lower surface of the base layer, the optical film with improved brightness and diffusion. 4. The method according to any one of claims 1 to 3,
The base layer has a thickness of 150 to 800㎛ thickness, and improved optical film and brightness. 4. The method according to any one of claims 1 to 3,
The round ring-shaped outer diameter is 50 to 180㎛, the inner diameter is 30 to 150㎛ characterized in that the brightness and diffusivity improved optical film. 4. The method according to any one of claims 1 to 3,
The round ring-shaped height is 10 to 50㎛ characterized in that the optical film with improved brightness and diffusion. 4. The method according to any one of claims 1 to 3,
The round annular spacing is 30 to 300㎛ characterized in that the optical film with improved brightness and diffusion. delete 4. The method according to any one of claims 1 to 3,
The base layer is methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate Homopolymers of monomers selected from latex, hydroxyethyl acrylate, acrylamide, metarollacrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate and 2-ethylhexyl acrylate, An optical film with improved brightness and diffusivity further comprising at least one light diffusing particle comprising a bead and a silicon-based spherical particle made of a copolymer or terpolymer, polyethylene, polystyrene, polypropylene, an acrylic and an olefin copolymer.

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