KR101255626B1 - Optical sheet for light extracting and beam-shaping for organic light emitting diodes - Google Patents

Abstract

The present invention relates to an optical sheet for an organic light emitting display device and an organic light emitting display device in which the optical sheet is disposed on an organic light emitting display device, and more particularly, a light extraction layer and a light extraction layer including a lens unit having a different refractive index. An organic sheet for an organic light emitting display device comprising a light collecting layer for collecting light emitted from the organic light emitting display device, and an organic light emitting display device having the optical sheet disposed on the organic light emitting display device.

In the case of using the optical sheet of the present invention comprising a light extraction layer including a lens portion having a different refractive index and a light collecting layer for changing the optical path, the optical sheet according to the present invention is formed by reflection and refraction made in the sheet having the multilayered composite structure. Only a single sheet can improve light extraction and control the beam profile.

OLED display, light extraction, condensing, total reflection, refractive index

Description

Optical sheet for light extracting and beam-shaping for organic light emitting diodes

The present invention relates to an optical sheet for an organic light emitting display device and an organic light emitting display device including the same, in particular comprising a light extraction layer and a light collecting layer including a lens portion having a high refractive index and a non-lens portion having a low refractive index, The present invention relates to an optical sheet having excellent light collecting performance and an organic light emitting display device including the same.

Currently, a cathode ray tube (CRT) is used as a main device in a display device such as a television or a monitor, but this has a problem of high weight and volume and high driving voltage. Accordingly, there is a need for a flat panel display device having excellent characteristics such as thinness, light weight, and low power consumption, and a liquid crystal display device, a plasma display device, a field emission display device, and an electroluminescence display device (LED) are emerging. Various flat panel display devices are being researched and developed.

The electroluminescent display device is a display device using an electroluminescence phenomenon in which light is emitted when a certain electric field is applied to a phosphor, and an organic light emitting display device and an organic light emitting display device (OLED or organic LED) according to the configuration of the light emitting layer. Can be divided into Among them, the organic light emitting display device is attracting attention as a natural color display device because light of all regions of visible light including blue is emitted, and has been widely used because of its high luminance and low operating voltage characteristics. In addition, because of self-luminous, high contrast, ultra-thin display is possible, and the process is simple, so there is relatively little environmental pollution.

1 illustrates a conventional organic light emitting display device, and as shown in FIG. 1, an anode 2, which is a transparent electrode, is formed on a glass substrate 1, and a hole injection layer 3 and an emission layer are formed thereon. (4) and the electron injection layer 5 are laminated, and the cathode 6 consisting of a metal electrode is formed on the electron injection layer.

The emission principle of the OLED is light emission by combining electrons and holes. When a driving voltage is applied to the anode 2 and the cathode 6, holes and electrons in the hole injection layer 3 are applied. The electrons in the injection layer 5 respectively propagate toward the light emitting layer 4 and combine in the light emitting layer 4 to emit visible light. Thus, an image or an image is displayed by the visible light generated from the light emitting layer 4.

In the structure shown above, the light exit direction is indicated by an arrow, and the light emitted from the light emitting layer 4 is emitted into the air through the transparent materials of the anode and the glass substrate, which are transparent electrodes. Due to the difference in the refractive index of each layer constituting the light emitting device, in particular, the difference in the refractive index between the glass substrate and the air, some of the emitted light is lost due to internal reflection which is reflected in the inner direction, thereby substantially extracting light. The efficiency is reduced.

Accordingly, various light extraction films have been developed for extracting light from the organic light emitting display, and the conventional light extraction film includes most uneven parts. Such a conventional light extraction film may be easily scratched in the shape of the uneven portion, thereby reducing the light extraction efficiency or the uniformity of the light extraction may cause an appearance problem. On the other hand, the light extracted through the light extraction film is emitted in a state in which the beam profile (beam profile) is not determined to suit the purpose, there is a problem that the light condensing efficiency and the front brightness is lowered.

Therefore, there is a need for a new optical sheet having a multi-layered composite function capable of preventing the loss of light due to total internal reflection and the like to improve the efficiency of light and to control the beam profile by collecting visible light.

Accordingly, an aspect of the present invention is to provide an optical sheet for an organic light emitting display device having a composite structure, which increases light utilization efficiency without controlling uneven portions and simultaneously controls an optical path.

Accordingly, another aspect of the present invention is to provide an organic light emitting display device in which the sheet is disposed above the organic light emitting display device.

According to an aspect of the present invention, an optical sheet for an organic light emitting display device includes a light extraction layer including a lens unit having a high refractive index and a non-lens unit having a low refractive index, and a light collecting layer for collecting light emitted from the light extraction layer. Is provided.

Preferably, the lens portion is in the shape of a hemispherical lens, a pyramidal lens, a conical lens, a conic lens, a lenticular lens, a prism lens, a concave lens or a diffused particle.

The refractive index of the lens portion of the light extraction layer is preferably less than 0.2 that is different from the refractive index of the glass substrate of the organic light emitting display device.

The refractive index of the non-lens portion of the light extraction layer is larger than the refractive index of air and smaller than the refractive index of the lens portion, and the difference in refractive index between the non-lens portion and the lens portion is preferably 0.1 or more.

The light collecting layer is preferably formed of a prism lens, a lenticular lens, a micro lens array, or a Fresnel lens.

It is preferable to further include a reflective layer between the light extraction layer and the light collecting layer.

It is preferable to further include at least one light extraction layer, a light collecting layer, or a light extraction layer and a light collecting layer between the light extraction layer and the light collecting layer.

The two or more light collecting layers are preferably arranged such that their extending directions are perpendicular to each other.

According to another aspect of the present invention, there is provided an organic light emitting display device in which the optical sheet is disposed on an organic light emitting display device.

According to still another aspect of the present invention, an optical sheet, a transparent electrode which is an anode, a hole injection layer, a light emitting layer, an electron injection layer and a metal electrode, the optical sheet includes a light extraction layer including a lens portion and a non-lens portion, and An organic light emitting display device includes a light collecting layer for collecting light emitted from the light extracting layer, wherein a refractive index of the lens unit of the light extracting layer is greater than that of the non-lens unit.

In the case of using the optical sheet for an organic light emitting display device of the present invention comprising a light extracting layer including a lens portion having a large refractive index, a non-lens portion having a lower refractive index, and a light collecting layer for condensing to improve front brightness. The reflection and refraction made in the sheet having the complex structure can enhance the light extraction effect and control the beam profile with only a single sheet according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sheet for use in an organic light emitting display (OLED), wherein a plurality of layers having a structure capable of causing reflection and refraction are formed inside a film having a multilayer structure to extract light of the organic light emitting display. You can increase the effect and control the beam profile.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The optical sheet of the present invention includes a light extraction layer and a light collecting layer, and the light extraction layer includes a lens portion having a high refractive index and a non-lens portion having a low refractive index.

2 (a) shows an exemplary perspective view of an optical sheet according to the present invention. Referring to this, the optical sheet of the present invention may include a light extraction layer 10 and one or more light collection layers 13 'and 13' ''. The light extraction layer 10 includes a lens portion 11 having a high refractive index and a non-lens portion 12 having a lower refractive index than that shown in FIG. 3 (b). The optical sheet of the present invention may be composed of a plurality of layers including at least one light collecting layer 13 for collecting light emitted from the light extraction layer.

The non-lens portion 12 of the light extraction layer 10 is a transparent material that can transmit light with a visible light transmittance of about 85% or more, and the refractive index of the non-lens portion is greater than that of air and the lens portion 11 It is less than the refractive index of, the refractive index difference between the non-lens portion and the lens portion is not particularly limited as long as the material is not more than 0.1, for example, may be composed of a resin, plastic and glass. That is, for example, when the refractive index of the lens unit is 1.5, the refractive index of the non-lens unit may be greater than 1 to 1.4 or less. On the other hand, the larger the difference in refractive index between the non-lens portion and the lens portion is advantageous. This is because, in general, the larger the difference in refractive index, the higher the degree of freedom for refraction / reflection of light due to the lens shape, which is advantageous for the role as a lens.

The lens unit 11 included in the light extraction layer 10 is made of a transparent material having a refractive index similar to that of the glass substrate of the organic light emitting display device, thereby increasing light emission efficiency by refracting light emitted from the glass substrate. The lens may be in the form of a hemispherical lens, a pyramidal lens, a conical lens, a conic lens, a lenticular lens, a prism lens, a concave lens, or a diffuse particle. However, it is not limited to the lens having the above shape, for example, in the structure of the pyramidal lens can be applied to various types of lens shape including a state in which the top is cut, a polyhedron or more than a hexahedron. That is, by forming the lens portion of the various forms it is possible to improve the light efficiency by reducing the total internal reflection and to increase the light emission effect even if the size is not uniform, but uniform size to maximize the efficiency and to provide some light converging effect It is preferred to have In the case of a hemispherical lens, a pyramidal lens, a lenticular lens or a prism lens, as shown in FIG. 3 (b), the lens unit is preferably formed to be in contact with a surface opposite to the surface on which the light collecting layer is disposed in the light extraction layer. The lens unit may be included in the light extraction layer in the form of diffused particles. 2 (b) shows an exemplary optical sheet of the present invention including a light extraction layer 10 including a pyramidal lens portion.

Preferably, the distance between the lens portions is 10 to 500 μm, and the area of the bottom surface of the lens portion in contact with the light extraction layer is preferably 80 to 142% of the distance between the lenses, and the height of the lens portion is It is preferable that it is 20 to 100% of the original equivalent diameter of the base.

The lens unit of the light extraction layer may include a resin, plastic, glass, etc. as long as the visible light transmittance is about 85% or more and is a transparent material that can transmit light, but the refractive index of the lens unit is not limited. It is preferably similar to the refractive index of a transparent substrate such as a glass substrate located at and larger than the refractive index of the non-lens portion. That is, as shown in FIG. 3A, light emitted from the light emitting layer is emitted to the outside through the anode 2 and the transparent substrate 1, which are transparent electrodes of the organic light emitting display device. A portion of the light emitted from the air may not escape the flat transparent substrate due to the difference in refractive index between the air and the transparent substrate. That is, the scattered light component that emits light above the critical angle between two media having large refractive index differences is not emitted to the outside and is lost due to total internal reflection, thereby reducing light emission efficiency.

On the other hand, in the case of using the optical sheet of the present invention, as shown in Fig. 3B, the light extraction effect of the light emitted by the lens portion having the refractive index similar to that of the transparent substrate is improved. In more detail, the refractive index of the lens unit is preferably less than 0.2 that is different from the refractive index of the transparent substrate. When the refractive index is within the above range, the effect of preventing reflection of light occurring at the bottom of the lens unit is excellent. On the other hand, when the difference between the refractive index of the transparent substrate is 0.2 or more, the amount of light lost by total internal reflection due to the difference in refractive index at the boundary between the transparent substrate and the optical sheet is greatly increased, thereby reducing the improvement effect due to the lens shape of the light extraction layer.

The light collecting layer improves front luminance and light collecting efficiency by controlling a path of light emitted from the light extracting layer. The light collecting layer included in the optical sheet of the present invention is disposed on the light extracting layer, and the light collecting layer is a prism lens, lenticular lenses extending in one direction, or a micro lens array or a Fresnel lens. It can be formed, but is not particularly limited to the shape and may be any sheet having a light converging effect for controlling the light path. The beam profile is controlled by the condensing layer to condense outgoing light.

The optical sheet of the present invention may further include at least one light extracting layer, a light collecting layer, or both the light extracting layer and the light collecting layer between the light extracting layer and the light collecting layer. 2 (a) is an exemplary embodiment of the present invention having a plurality of light collecting layers arranged such that the light extraction layer 10 having the hemispherical lens portion and the two prism-shaped light collecting layers 13 ', 13' '' are orthogonal to each other. The structure is shown.

Furthermore, a reflective layer may be additionally included between the light extraction layer and the light collecting layer, and when the reflective transparent optical sheet is disposed on the opposite side of the light emitting surface, light that may be lost by total internal reflection, etc. is reflected to the light emitting surface. The luminous efficiency can be further improved. In more detail, the reflective layer may be formed in a region corresponding to the non-lens portion of the light extraction layer. The reflective layer may be formed by deposition or deposition through various methods, and thus may be manufactured through a separate process from the organic light emitting display device.

In the manufacture of the optical sheet of the present invention, the light extraction layer may be prepared by etching a non-lens portion formed of a resin or the like into a shape, and then filling a material having a refractive index greater than that of the non-lens portion in the etched groove. Furthermore, the light collecting layer or the additional light extraction layer, the light collecting layer, or the reflective layer may be bonded to each other by applying a transparent optical adhesive or a transparent resin between the respective layers to prepare the optical sheet of the present invention.

The transparent optical adhesive that can be used in the present invention is preferably made to be similar to the refractive index of the light emitting surface constituting the organic light emitting display device, for example, the transparent substrate, so as to prevent total internal reflection by the optical adhesive.

The thickness of the optical sheet of the present invention including the light extraction layer and the light collecting layer is preferably in the range of several tens to hundreds of micrometers, and the light extraction and condensing effect without significantly increasing the thickness of the light emitting device when it does not exceed a maximum of 1mm. Can be obtained. However, the present invention is not limited by the thickness of the optical sheet, and the thickness can be adjusted as necessary.

The optical sheet according to the present invention obtained above may be disposed on a transparent substrate of the organic light emitting display device to increase light utilization efficiency of light emitted from the transparent substrate and to control a beam profile.

According to another aspect of the present invention, there is provided an organic light emitting display device in which the optical sheet according to the present invention is disposed above the organic light emitting display device. More specifically, as illustrated in FIG. 4, the anode 2, which is a transparent electrode, is formed in contact with the optical sheet 20 according to the present invention, and the hole injection layer 3, the light emitting layer 4, and the electrons are formed. An organic light emitting display device is provided in which an injection layer 5 is stacked and an anode 6 formed of a metal electrode is formed on an electron injection layer. In this case, the refractive index of the lens portion of the light extraction layer is preferably similar to the refractive index of the anode 2 which is a transparent electrode, and more preferably, the difference in refractive index between the lens portion and the anode is less than 0.2.

The refractive index of the non-lens portion 12 of the light extraction layer 10 is greater than the refractive index of the air and smaller than the refractive index of the lens portion 11, and the difference in refractive index between the non-lens portion and the non-lens portion is particularly limited. Or, for example, resin, plastic, glass, and the like. In the above case, the glass means a case where the glass substrate itself is used as the light extraction layer, and the glass may be deposited on a glass substrate having a shape.

The lens unit 11 included in the light extraction layer 10 may have a hemispherical lens, a pyramidal lens, a conical lens, a conic lens, a lenticular lens, a prism lens, a concave lens, or a shape of diffused particles. However, it is not limited to the lens having the above shape. The lens unit may be formed to be in contact with a surface opposite to a surface on which the light collecting layer is disposed in the light extraction layer, and the lens unit may be included in the light extraction layer in the form of diffused particles.

Preferably, the distance between the lens portions is 10 to 500 μm, and the area of the bottom surface where the lens portion is in contact with the light extraction layer is 80 to 142% of the distance between the lenses, and the height of the lens portion is the bottom surface. It is preferable that it is 20 to 100% of the original equivalent diameter of.

If the lens portion of the light extraction layer is a transparent material that can transmit light with a visible light transmittance of about 85% or more and includes a resin, plastic, and glass, and the like, but is not particularly limited, the refractive index of the lens portion of the anode is a transparent electrode It is preferable that the refractive index is similar to and larger than the refractive index of the non-lens portion. More specifically, the refractive index of the lens unit is preferably less than 0.2 the difference between the refractive index of the anode, when having a refractive index within the above range is excellent in preventing the reflection of light occurring at the bottom of the lens unit.

The path of light emitted from the light extraction layer is then controlled by the light collecting layer of light. The light collecting layer may be a prism lens, a lenticular lens extending in one direction, or may be formed of a micro lens array or a Fresnel lens, but is not particularly limited to the shape and has a light collecting effect for controlling the light path. Any sheet having can be used.

The light extracting layer and the light collecting layer may further include at least one or more light extraction layers, a light collecting layer, or both the light extraction layer and the light collecting layer. Furthermore, a reflection layer may be further included between the light extraction layer and the light collection layer so that the light, which may be lost due to total internal reflection, may be reflected to the light emitting surface to further improve the light emission efficiency.

In the manufacture of the organic light emitting display device of the present invention, the organic light emitting display device is manufactured by attaching the optical sheet according to the present invention on the organic light emitting device glass substrate produced through a conventional organic light emitting device (OLED) manufacturing process or , Replacing the glass substrate (1) used in the manufacture of the organic light emitting device with the optical sheet of the present invention, the optical sheet of the present invention, the anode (2), the hole injection layer (3), the light emitting layer (4), electron injection of the transparent electrode It can be produced by the method of depositing the layer 5 and the cathode 6 which is a metal electrode in sequence.

In this case, the optical sheet of the present invention is manufactured through a mold, manufactured by an injection process, or etched a glass substrate in a method that can be cured by heat, cooling or light in a resin or other liquid state on a polymer substrate or a glass substrate. The first step of forming the lens shape of the light extraction, such as by manufacturing to have a shape on the glass substrate itself through the process, by applying a resin or other liquid polymer on the lens portion formed in the first step and then cooling or A second step of forming a non-lens layer by curing with light or glass deposition process such as FHD (Flame Hydrolysis Deposition) in the case of glass, and a third step of attaching the light extraction layer and the optical sheet of the light collection layer formed as described above. It can be prepared through the steps. In addition, if necessary, the processes of the second and third steps may be repeatedly applied, and the shape may be manufactured to have a shape that meets the purpose of each layer related to light extraction, condensation, or reflection.

The organic light emitting diode display according to the present invention obtained as described above may increase the light utilization efficiency of the emitted light and control the beam profile.

FIG. 1 shows a general organic light emitting diode having a cathode 6 formed of a transparent electrode, a cathode 2, a hole injection layer 3, a light emitting layer 4, an electron injection layer 5, and a metal electrode on a glass substrate 1. A cross-sectional view of the display device is shown.

2 (a) is an exemplary embodiment of the present invention having a plurality of light collecting layers arranged such that the light extraction layer 10 having the hemispherical lens portion and the two prism-shaped light collecting layers 13 ', 13' '' are orthogonal to each other. The structure in which the optical sheet is disposed in the organic light emitting display device is illustrated.

FIG. 2 (b) shows an exemplary optical sheet of the present invention comprising a light extraction layer 10 including a pyramidal lens portion and a light collecting layer 13 ′ ″ formed by periodically arranging lenticular lenses extending in one direction. Shows a structure arranged in an organic light emitting display device.

3 (a) illustrates typical optical paths of the structure of a general organic light emitting display device and light emitted from the light emitting layer to the outside through the hole injection layer, the transparent electrode, and the transparent substrate.

3B illustrates at least one light extracting layer 10 including a lens unit 11 and a non-lens unit 12 having different refractive indices, and at least one light collecting layer for condensing light emitted from the light extracting layer. A cross-sectional view of an organic light emitting display device in which an exemplary optical sheet 20 of the present invention composed of a plurality of layers including (13) is disposed is shown.

4 shows an anode 2 which is a transparent electrode on the optical sheet 20 according to the present invention, on which a hole injection layer 3, a light emitting layer 4 and an electron injection layer 5 are stacked. FIG. 4 illustrates an exemplary organic light emitting display device having a cathode 6 formed of a metal electrode on an electron injection layer.

Claims (17)

A light extraction layer including a lens unit and a non-lens unit, and Condensing layer for condensing the light emitted from the light extraction layer, It includes a reflective layer between the light extraction layer and the light collecting layer, An optical sheet for an organic light emitting display device, wherein the refractive index of the lens portion of the light extraction layer is larger than that of the non-lens portion. The optical sheet of claim 1, wherein the lens unit has a shape of a hemispherical lens, a pyramidal lens, a conical lens, a conic lens, a lenticular lens, a prism lens, a concave lens, or a diffused particle. The optical sheet for an organic light emitting display device of claim 1, wherein a refractive index of the lens unit of the light extracting layer has a value less than 0.2 from a refractive index of the glass substrate of the organic light emitting display device. The optical sheet of claim 1, wherein a refractive index of the non-lens portion of the light extraction layer is larger than a refractive index of air and smaller than a refractive index of the lens portion, and a difference in refractive index between the non-lens portion and the lens portion is 0.1 or more. . The optical sheet of claim 1, wherein the light collecting layer is formed of a prism lens, a lenticular lens, a micro lens array, or a Fresnel lens. delete The optical sheet of claim 1, further comprising at least one light extracting layer, a light collecting layer, or both a light extracting layer and a light collecting layer between the light extracting layer and the light collecting layer. The optical sheet of claim 7, wherein the two or more light collecting layers are arranged such that their extending directions are perpendicular to each other. An optical sheet according to any one of claims 1 to 5 and 7 to 8, comprising a glass substrate, a transparent electrode, a hole injection layer, a light emitting layer, an electron injection layer and a metal electrode. Organic light emitting display device is disposed. And an optical sheet, a transparent electrode, a hole injection layer, a light emitting layer, an electron injection layer, and a metal electrode, wherein the optical sheet condenses light emitted from the light extraction layer and a light extraction layer including a lens unit and a non-lens unit. And a reflective layer between the light extraction layer and the light extraction layer, wherein the refractive index of the lens portion of the light extraction layer is greater than that of the non-lens portion. The organic light emitting display device of claim 10, wherein the lens unit has a shape of a hemispherical lens, a pyramidal lens, a conical lens, a conic lens, a lenticular lens, a prism lens, a concave lens, or a diffused particle. The organic light emitting display device of claim 10, wherein a refractive index of the lens unit of the light extraction layer has a value less than 0.2 from a refractive index of the anode, which is a transparent electrode. The organic light emitting display device of claim 10, wherein a refractive index of the non-lens portion of the light extraction layer is greater than a refractive index of air and less than a refractive index of the lens portion, and a difference in refractive index between the non-lens portion and the lens portion is 0.1 or more. The organic light emitting display device of claim 10, wherein the light collecting layer is formed of a prism lens, a lenticular lens, a micro lens array, or a fresnel lens. delete The organic light emitting display device of claim 10, further comprising at least one light extracting layer, a light collecting layer, or both a light extracting layer and a light collecting layer between the light extracting layer and the light collecting layer. The organic light emitting display device of claim 16, wherein the two or more light collecting layers are disposed such that their extending directions are perpendicular to each other.

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