KR20050081361A - Film of light scattering, method for manufacturing the same, and display device - Google Patents

Abstract

 Disclosed are a light scattering film for improving display quality, a method of manufacturing the same, and a display device thereof. The light scattering film has a first region having a relatively high height and a relatively low height, and the first region has a closed curve shape. Microlenses are defined by the first region portions, and the microlenses have an irregular array structure, scatter external light provided from one side, and scatter internal light provided from the other side. Let's do it. Therefore, the reflectance of the external light incident on the surface is reduced, and the internal light reaching the surface of the display device is emitted to the outside to improve the external light extraction efficiency.

Description

Light scattering film, its manufacturing method, and display apparatus {FILM OF LIGHT SCATTERING, METHOD FOR MANUFACTURING THE SAME, AND DISPLAY DEVICE}

The present invention relates to a light scattering film, a manufacturing method and a display device thereof, and more particularly, to a light scattering film for improving display quality, a manufacturing method and a display device thereof.

In general, an electronic display device is a device that transmits various pieces of information to a human through vision. That is, an electronic display device may be defined as an electronic device that converts electrical information signals output from various electronic devices into optical information signals that can be recognized by a human vision, and plays a role of a bridge that connects humans and electronic devices. It can be defined as.

On the other hand, due to the rapid progress of semiconductor technology, electronic display devices suitable for a new environment, that is, thin and light, low driving voltage and low power consumption, according to the miniaturization and low voltage and low power of various electronic devices, and small and light electronic devices. There is an increasing demand for a flat panel display device having the characteristics of.

Among the various flat panel displays currently developed, the liquid crystal display is thinner and lighter than other display devices, and is widely used in various electronic devices because it has low power consumption and low driving voltage and can display images close to the cathode ray tube. have. In addition, since the liquid crystal display device is easy to manufacture, its application range is further expanded.

In addition, as the organic electroluminescent display device of the flat panel display device is used as a display device such as a notebook, the demand thereof is increasing. In this case, the organic light emitting display device is a display device that emits light when a current is applied to the fluorescent organic compound. The organic light emitting display device displays an image by driving N × M organic light emitting cells. In this case, the organic light emitting cell is an organic light emitting diode having a structure of an anode, an organic thin film, and a cathode electrode layer.

In the liquid crystal display and the organic light emitting display, when the reflection is prevented by external light such as sunlight or fluorescent light, the contrast is lowered and the display quality is lowered.

Therefore, in order to reduce the reflectance of the external light, an antireflection film such as an antireflection film or a circular polarizer is used.

The anti-reflection film is formed by stacking a high refractive index material layer and a low refractive index material layer on a substrate such as a liquid crystal display or an organic electroluminescent display to prevent reflection of the external light.

In addition, the anti-reflection film is composed of a linearly polarized film for linearly polarizing light and a quarter-wave plate (90) to rotate the polarization of the light transmitted through the position positioned below the linearly polarized film 90 degrees. In this case, an anti-glare layer and a protective film are formed on the anti-reflection film as necessary.

The reflection principle of external light by the antireflection film of the above-mentioned structure is as follows.

In other words, when external light passes through the protective film layer and passes through the linear flat tube film, the linear light is linearly directed in a predetermined direction. Subsequently, when the linearly condensed light passes again through the lower quarter wave plate, the polarization state is changed to circularly polarized light. The circularly polarized light is changed into a mirror-symmetric circularly polarized state on the substrate of the liquid crystal display or the organic electroluminescent display, and the light passes through the quarter wave plate again and is perpendicular to the polarization direction of the linearly polarized film. Will change to a linear state. Therefore, the reflected light cannot pass through the linearly polarized film located on the upper side of the quarter wave plate, thereby suppressing reflection of external light.

On the other hand, in the organic light emitting display, when the anti-reflection film or the anti-reflection film is used to prevent reflection of external light, the external light extraction efficiency is reduced to 10% or less.

That is, the light generated by the organic light emitting display device forms a plate between the ITO film as the anode and the metal film as the cathode and the interface between the organic substrate and the cathode, so that about 50% of the emitted light cannot be extracted to the outside. It is totally reflected at the interface between the substrate and air, and about 30% is lost and cannot be extracted to the outside. Therefore, the external light extraction efficiency of the light emitted from the organic light emitting display device is about 20%. However, when using the anti-reflection film or the anti-reflection film for external light reflection, the external light extraction efficiency is reduced to about 10%.

As described above, since the anti-reflection film and the anti-reflection film for reducing the reflection of external light of the liquid crystal display and the organic light emitting display device are too expensive, there is a problem that the manufacturing cost increases.

In addition, the organic light emitting display device using the antireflection film and the antireflection film having the above-described configuration has a problem in that external light extraction efficiency is lowered.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, an object of the present invention to provide a light scattering film for preventing the reflection of external light incident on the display device, and improve the external light extraction efficiency of the internal light. Is in.

Another object of the present invention is to provide a method for producing the light scattering film.

Another object of the present invention is to provide a display device having the light scattering film.

The light scattering film according to the present invention for achieving the above object has a first region having a relatively high height and a second region having a relatively low height, surrounding the first region in a closed curve form The microlenses are defined by the first region portions, and the microlenses have an irregular array structure, scatter the external light provided from one side, and scatter the internal light provided from the other side.

The light scattering film according to the present invention forms a master mold having a master pattern for forming microlenses having a first diameter of an irregular array structure, and duplicates the master mold to form a working mold having a walking pattern opposite to the master pattern. Form. Next, the microlenses are formed by soft molding using a working mold.

The display device according to the present invention is formed on a display panel for displaying an image and an irregular array structure formed on one surface of the display panel to prevent reflection of external light provided from one side and to improve external extraction efficiency of the internal light provided from the other side. Light scattering films with microlenses.

According to the present invention, the external light incident on the surface is scattered to reduce the reflectance, and the internal light reaching the surface of the display is scattered and emitted to the outside to improve the external light extraction efficiency.

Hereinafter, a display device and a manufacturing method thereof according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view schematically showing the configuration of a display device according to the present invention.

As shown in FIG. 1, the display device 100 according to the present invention includes an anode electrode 220 and an organic electroluminescent layer (hereinafter referred to as an organic EL layer) 230 on one surface of the transparent glass substrate 210. ) And the cathode electrode 240 sequentially include the display panel 200.

Here, the anode electrode 220 is formed by patterning a transparent electrode forming material in a predetermined shape. The organic EL layer 230 is composed of one or more organic thin films. That is, in the organic EL layer 230, a hole injection layer (HIL), a hole transfer layer (HTL), an emission layer (EL), and an electron injection layer (EIL) are sequentially formed. It is formed by laminating. The cathode electrode 240 is a metal electrode formed of a metal material.

When a driving voltage is applied to the anode electrode 220 and the cathode electrode 240, holes in the hole injection layer and electrons in the electron injection layer in the organic EL layer 230 respectively move toward the light emitting layer to excite the light emitting layer. In addition, the excited light emitting layer emits visible light. Therefore, the display device 100 displays an image by the visible light emitted from the light emitting layer.

In addition, the display device 100 further includes a light scattering film 300 formed on the other surface of the transparent glass substrate 210. Here, the light scattering film 300 is laminated on the transparent glass substrate 210 by the adhesive 400 formed on the other surface of the transparent glass substrate 210.

The light scattering film 300 includes a base film 310 and a plurality of microlenses 320 having an irregular array structure formed on the surface of the base film 310.

The light scattering film 300 will be described in more detail with reference to FIG. 2.

FIG. 2 is an enlarged view of portion “A” shown in FIG. 1.

As shown in FIG. 2, the light scattering film 300 is divided into relatively thin first region portions 320a and relatively thick second region portions 320b by the thickness of the base film 310. . That is, the first region portions 320a have a lower height than the second region portions 320b and are formed to surround the second region portions 320b in a closed curve shape.

Therefore, the plurality of microlenses 320 are formed by the first region portions 320a and the second region portions 320b. Here, the microlens 320 has a convex lens shape enclosed in a closed curve shape. In addition, the microlens 320 has a circular or elliptical cross section cut parallel to the transparent glass substrate 210. The diameter of the microlens 320 is formed in the range of 1 to 10㎛, the optimum diameter is about 5㎛.

In addition, the microlens 320 has a lower refractive index than glass and is formed of a transparent insulating material having a higher refractive index than air. For example, the microlens 320 is formed of silicon oxide (SiO ₂ ) or the like.

The plurality of microlenses 320 formed on the light scattering film 300 are irregularly arranged by a random number determined by applying Monte Carlo method and molecular dynamics technology.

Referring back to FIG. 1, the light scattering film 300 having the above configuration scatters, that is, diffusely reflects, external light L1 incident on the display device 100 by the plurality of microlenses 320 to reduce reflectance. Let's do it.

In addition, the light scattering film 300 scatters the internal light L2 reaching the surface of the display device 100 so as to control the light path so that the internal light L2 is emitted to the outside to increase the external light extraction efficiency. Is improved.

Referring to the accompanying drawings, the manufacturing process of the light scattering film of the display device according to the present invention having the above configuration will be described in detail as follows.

3A to 3F are cross-sectional views illustrating a manufacturing process of the light scattering film shown in FIG. 1.

As shown in FIG. 3A, an insulating film 510 is formed on the entire surface of the first substrate 500. Here, the insulating film 510 is formed of a photoresist which is a photosensitive insulating film. Accordingly, the exposed region or the unexposed regions of the insulating layer 510 are etched according to the characteristics of the photoresist.

Referring to FIG. 3B, a mask 520 having a predetermined pattern is formed on the first substrate 500 on which the insulating layer 510 is formed. In this case, the mask 520 has an opening 525 corresponding to the exposure area.

Subsequently, the insulating film 510 is exposed to ultraviolet light (UV) using the mask 520 and then developed using a tetramethyl-ammonium hydroxide (TMAH) developer. As a result, the insulating layer 510 of the exposed region is removed to form the microlens pattern 530 for forming the microlens 310 of FIG. 1.

As illustrated in FIG. 3C, the hard-baking process and the curing process may be performed on a first substrate 500 on which the microlens pattern 530 is formed in a furnace or oven 700 at 200 ° C., respectively. The tilt of the microlens pattern 530 is adjusted by performing for 1 hour or more. Thus, the microlens pattern 530 is formed in a closed curve shape.

In this case, when the microlens pattern 530 is cut in a direction parallel to the first substrate 500, the microlens pattern 530 has a circular or elliptical cut surface. In addition, the microlens pattern 530 has a diameter of about 3㎛, and the formation interval between the microlens patterns 530 is about 2㎛.

Next, referring to FIG. 3D, a metal material is stacked on the first substrate 500 on which the microlens pattern 530 is formed to have a uniform thickness of about 1 μm to have a shape corresponding to the microlens 310 of FIG. 1. The master mold 550 having the master pattern 540 is completed. In this case, the master pattern 540 has a convex lens shape similarly to the microlens 310 of FIG. 1, and has a diameter of about 5 μm.

Here, the master mold 550 has a diameter of about 3 μm, and a microlens pattern 530 having a formation interval of about 2 μm is first formed, and then a master of about 5 μm in diameter is deposited by laminating metal materials. The reason for forming the pattern is as follows.

That is, when determining the irregular number of the microlenses for the microlens 320 of the light scattering film 300 to have an irregular arrangement structure, there should be a spacing between the microlenses of about 2 μm.

Therefore, a microlens pattern having a diameter of about 3 μm and a formation interval of about 2 μm is first formed, and a metal layer having a thickness of about 1 μm is formed on the microlens pattern to have a master pattern having a diameter of about 5 μm. To form. Therefore, the light scattering film having a microlens having a diameter of about 5 μm can be formed by the master pattern.

As shown in FIG. 3E, the master mold 550 is replicated to form a plurality of working molds 600. Here, the working mold 600 has a working pattern 620 patterned in such a manner that a second insulating film (not shown) formed on the second substrate 610 is engaged with the master pattern 530. That is, the working pattern 620 has a concave lens shape opposite to the convex lens shape master pattern 540. At this time, the working pattern 620 has a diameter of about 5㎛.

Referring to FIG. 3F, a microlens 320 having an irregular array structure is formed on a surface by a soft molding process in which a working mold 600 is placed on a base film 310 and then heated. In this case, the microlens 320 is divided into first region portions 320a and second region portions 320b formed at a relatively high level.

Here, the first region portions 320a have a lower height than the second region portions 320b and are formed to surround the second region portions 320b in a closed curve shape. Therefore, the plurality of microlenses 320 are defined by the first region portions 320a and the second region portions 320b. In particular, the plurality of microlenses 320 have a convex lens shape defined by the second region portions 320b. As a result, the light scattering film 300 is completed.

The light scattering film 300 completed through the above process is laminated on the other surface of the transparent glass substrate 210 of the display device 100. That is, the adhesive 400 as shown in FIG. 1 is formed on the other surface of the transparent glass substrate 210 of the display device 100, and the light scattering film 300 is formed by the adhesive 400 to the transparent glass substrate 210. On the other side of the substrate. Thus, the display device 100 according to the present invention is completed.

Meanwhile, in the present invention, the case where the convex lens-shaped microlens is formed is described as an example, but FIG. 4 is a cross-sectional view illustrating another configuration example of the light scattering film illustrated in FIG. 1, and as shown in FIG. The microlens 330 may be formed.

That is, the microlens 330 is formed so that the concave portions 330b having relatively thin thicknesses of the base film 310 are surrounded by closed curves. Thus, the light scattering film 300 has a concave microlens 330. At this time, the microlens 330 has a diameter of about 5㎛.

As described above, when the light scattering film 300 is formed by the master mold 550 having the microlens pattern 530 having a diameter of about 3 μm, the flat portion where the mirror reflection of external light occurs is light. 75% of the total area of the scattering film 300.

On the contrary, when the light scattering film is formed by the master mold 550 having the master pattern 540 having a diameter of about 5 μm formed by depositing a metal material on the microlens pattern 530, mirror reflection occurs. The flat portion is reduced to 9.4% of the total area of the light scattering film 300. Therefore, the reflection of the external light by the mirror reflection is significantly reduced.

In addition, the present invention has been described in the case of forming a microlens by a master mold having a master pattern by forming a microlens pattern having a diameter of about 3㎛ first and then forming a metal layer having a thickness of about 1㎛, for example, about 5 Microlenses can be formed by a master mold having a microlens pattern having a diameter of μm.

5 is a graph illustrating the reflectance of the display device according to the present invention.

Referring to FIG. 5, (a) shows a reflectance when a light scattering film 300 having a microlens with a diameter of 5 μm is formed, (b) shows a reflectance when a conventional circular polarizer is formed, and (c) Represents the reflectance when the light scattering film and the circular polarizing plate are not formed.

That is, as shown in Table 1 below, when a light scattering film having a microlens having a diameter of 5 μm is formed (a), the reflectance of external light is about 1.83 (%), and when the circular polarizer is formed (b), the reflectance is About 0.67 (%). In addition, when the light scattering film or the circular polarizing plate is not formed (c), the reflectance is about 60.10 (%). At this time, the incident angle of the external light is about 30 degrees.

Table 1 shows the reflectance when the light scattering film or the circular polarizing plate is formed.

Light Scattering Film (X) Circular Polarizer (X) Light Scattering Film (5㎛ Diameter) Light Scattering Film (3㎛ Diameter) Circular polarizer reflectivity(%) 60.10 1.83 12.82 0.67

As such, when the light scattering film is formed, the display device has a reflectance of the external light greatly reduced, and thus has a close reflectance when the conventional circular polarizer is formed. Therefore, the present invention can improve the display quality by reducing the reflectance without using an expensive circular polarizer by the light scattering film.

Meanwhile, (d) shows a reflectance of the display device in which a light scattering film having a microlens having a diameter of about 3 μm is formed by the master mold 550 having only the microphone lens pattern 530 of FIG. 3C, rather than (a). It has a large reflectance of about 12.82 (%). This is due to the specular reflection that occurs in the flat portions that exist between the microlenses of 3 mu m diameter. However, even when a light scattering film having a microlens having a diameter of 3 μm is formed, the reflectance can be greatly reduced rather than (c).

In addition, the microlens 320 of the light scattering film 300 scatters the internal light L2 that reaches the surface of the transparent glass substrate 210, and thus the internal light L2 is emitted to the outside, thereby providing external light. Extraction efficiency is improved. That is, as the light reaches the surface of the transparent glass substrate 210 and is reflected by the mirror, the internal light L2 that is not extracted to the outside is scattered by the microlens 320 of the light scattering film 300, thereby The route has been changed and exited. Therefore, the external light extraction efficiency of the display device 100 is improved.

Table 2 shows the luminance of the display device according to the present invention.

Light Scattering Film Circular polarizer (X) Circular polarizer Luminance (cd / m ² ) 181 145 52

As shown in Table 2, when the luminance was measured in the dark room, the luminance of the display device on which the circular polarizer was formed was 52, and the luminance of the display device on which the circular polarizer was not formed was 145. On the other hand, since the display device 100 on which the light scattering film 300 is formed has a luminance of 181, an external light extraction efficiency of about 24.8% is improved compared to the display device 100 on which the light scattering film 300 is not formed. do.

In the above description, the light scattering film is formed on the organic light emitting display as an example, but may be formed on other display devices, for example, a liquid crystal display.

As described above, according to the present invention, a light scattering film having a plurality of microlenses having an irregular array structure on its surface is formed on one surface of a display device.

Therefore, in the present invention, reflectance of external light is reduced by scattering, i.e., reflecting, external light by the microlenses of the light scattering film.

In addition, according to the present invention, as the internal light reaching the surface of the display device is scattered by the microlens of the light scattering film to adjust the light path, the internal light is emitted to the outside, thereby improving external light extraction efficiency.

Therefore, in the present invention, since the reflectance of the external light is reduced by the light scattering film and the external light extraction efficiency of the internal light is improved, display quality can be improved.

While the invention has been described with reference to the examples, those skilled in the art may variously modify and change the invention without departing from the spirit and scope of the invention as set forth in the claims below. You will understand.

1 is a cross-sectional view schematically showing the configuration of a display device according to the present invention.

FIG. 2 is an enlarged view of portion “A” shown in FIG. 1.

3A to 3F are cross-sectional views illustrating a manufacturing process of the light scattering film shown in FIG. 1.

4 is a cross-sectional view showing another example of the configuration of the light scattering film shown in FIG.

5 is a graph illustrating the reflectance of the display device according to the present invention.

* Description of the symbols for the main parts of the drawings *

100: display device 200: display panel

300: light scattering film 310: base film

320: microlens 400: adhesive

Claims (14)

First region portions having a relatively high height; And A second region having a relatively low height and surrounding the first region in a closed curve shape; The microlens is defined by the first region portions, the microlens has an irregular array structure, scatters the external light provided from one side, and scatters the internal light provided from the other side. The light scattering film of claim 1, wherein the microlenses have a diameter in the range of about 1 to about 10 μm. The light scattering film of claim 1, wherein the microlenses have a circular or elliptical cut surface. The light scattering film of claim 1, wherein the microlenses have a refractive index lower than that of glass and a refractive index higher than that of air. First region portions having a relatively low height; And A second region having a relatively high height and surrounding the first region in a closed curve shape; The microlens is defined by the first region portions, the microlens has an irregular array structure, scatters the external light provided from one side, and scatters the internal light provided from the other side. Forming a master mold having a master pattern for forming microlenses having a first diameter of an irregular array structure; And Duplicating the master mold to form a working mold having a working pattern opposite the master pattern; Forming the microlens by soft molding using the working mold. The method of claim 6, wherein forming the master mold Forming an insulating layer on the substrate; Patterning the insulating layer to form a microlens pattern having a second diameter smaller than the first diameter; Adjusting the inclination of the microlens pattern; And Forming a master pattern by forming a metal layer with a uniform thickness on a substrate on which the tilted microlens pattern is formed; The master pattern has a first diameter, characterized in that the manufacturing method of the light scattering film. The method of claim 6, wherein forming the master mold Forming an insulating layer on the substrate; Patterning the insulating layer to form a microlens pattern; And Adjusting the inclination of the microlens pattern to form the master pattern having the first diameter. A display panel displaying an image; And And a light scattering film formed on one surface of the display panel, the light scattering film having microlenses having an irregular array structure for preventing reflection of external light provided from one side and improving external extraction efficiency of internal light provided from the other side. The display device of claim 9, further comprising an adhesive member configured to laminate the light scattering film on one surface of the display panel. The method of claim 9, wherein the light scattering film First region portions having a relatively high height; And A second region having a relatively low height and surrounding the first region in a closed curve shape; And the microlens is defined by the first region portions. The method of claim 9, wherein the light scattering film First region portions having a relatively low height; And A second region having a relatively high height and surrounding the first region in a closed curve shape; And a micro lens is defined by the first region portions. 10. The display device according to claim 9, wherein the display panel is a liquid crystal display panel which displays an image including a liquid crystal layer. 10. The display device according to claim 9, wherein the display panel is an organic light emitting display panel including an organic light emitting element to display an image.