KR100722115B1 - Organic electroluminescent display - Google Patents

Abstract

The present invention relates to an organic light emitting display device which can prevent a decrease in contrast due to external light and improve brightness.

In the organic light emitting display device of the present invention, light extraction is formed on a lower substrate and an upper substrate, and a light control film for controlling light extraction is formed on at least one surface of the organic light emitting display device.

By such a configuration, it is possible to display an image having improved contrast in the outdoor with strong external light. In addition, since the light control film is not attached to the other surface of the pixel portion, the image of the high brightness can be displayed and be usefully used indoors.

Organic electroluminescent display, double sided light emission, light control film

Description

Organic Electro-Luminescence Display

1 is a diagram illustrating a cross-sectional structure of a pixel of a conventional double-sided organic light emitting display device.

2 is a diagram illustrating an organic light emitting display device according to an exemplary embodiment of the present invention.

3 is a cross-sectional view illustrating a pixel of the organic light emitting display device illustrated in FIG. 2.

4A to 4B are diagrams showing the configuration of the light control film shown in FIG.

<Explanation of symbols for the main parts of the drawings>

200: pixel portion 210: pixel

220: scan driver 230: data driver

310: lower substrate 320: semiconductor layer

330: gate insulating film 340: gate electrode

350: interlayer insulating film 360: source and drain electrodes

370: planarization film 380: organic light emitting diode

385: shield 390: upper substrate

400: light control film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent display, and more particularly, to an organic electroluminescent display which can prevent a decrease in contrast due to external light and improve luminance.

Recently, various flat panel display devices having a lighter weight and a smaller volume than the cathode ray tube have been developed, and in particular, electroluminescent display devices having excellent luminous efficiency, luminance, viewing angle, and fast response speed have been attracting attention.

Such electroluminescent displays include organic electroluminescent displays using organic light emitting diodes (OLEDs) and inorganic electroluminescent displays using inorganic light emitting diodes (LEDs). Among them, the organic light emitting display device uses an organic compound as a light emitting material, and is attracting attention as a next generation flat panel display device due to its excellent brightness and color purity. In addition, the organic light emitting display device is expected to contribute to the development of portable electronic devices because it is thin, light, and can be driven with low power.

Such an organic light emitting display device is divided into a top emission, a bottom emission, and a double emission organic light emitting display device according to a light extraction direction. Among these, the double-sided organic light emitting display device has a high light extraction direction in the direction of the upper substrate and the lower substrate, so that both the inner window and the outer window can be realized in one panel when manufacturing a mobile phone having an inner window and an outer window. I am getting it.

1 is a diagram illustrating a cross-sectional structure of a pixel of a conventional double-sided organic light emitting display device. In general, the pixel may include an organic light emitting diode, at least one capacitor, a transistor, and the like. For convenience, only an organic light emitting diode and a transistor connected to the organic light emitting diode will be shown in FIG. 1.

Referring to FIG. 1, a pixel of a conventional double-sided organic light emitting display device includes a transistor formed on a lower substrate 110 and an organic light emitting diode 180 formed to be connected to the transistor.

The transistor is formed on the lower substrate 110 and includes a semiconductor layer 120 including a source and drain region 120a and a channel region 120b, a gate insulating layer 130 formed on the semiconductor layer 120, and a gate. A gate electrode 140 formed on the insulating film 130, an interlayer insulating film 150 formed on the gate electrode 140, and an interlayer insulating film 150 formed on the insulating film 130 and electrically connected to the source and drain regions 120a. Source and drain electrodes 160 are included.

The planarization film 170 is formed on the transistor, and the organic light emitting diode 180 is formed on the planarization film 170.

The organic light emitting diode 180 includes an anode electrode 180a formed to be connected to a transistor, a light emitting layer 180b formed on the anode electrode 180a, and a cathode electrode 180c formed on the light emitting layer 180b. Here, the anode electrode 180a and the cathode electrode 180c are formed of a transparent or translucent material for double-sided light emission.

The passivation layer 185 and the upper substrate 190 are provided on the cathode electrode 180c.

Such a conventional double-sided organic light emitting display device emits light toward the upper substrate 190 and the lower substrate 110, thereby realizing both the inner window and the outer window with a single panel, and thus are widely used in portable electronic devices such as thin-film mobile phones. Used. However, the conventional double-sided organic light emitting display device does not have a device capable of increasing contrast or brightness in various environments such as indoors and outdoors. For example, when the conventional double-sided organic light emitting display is exposed to strong external light, there is a problem that contrast is reduced due to reflected light.

Accordingly, it is an object of the present invention to provide an organic electroluminescent display device capable of preventing contrast degradation due to external light and improving luminance.

In order to achieve the above object, the present invention provides an organic electroluminescent display in which light extraction is formed on a lower substrate and an upper substrate, wherein at least one surface of the organic electroluminescent display is formed with a light control film for controlling light extraction. An organic electroluminescent display is provided.

Preferably, the light control film is characterized in that the polarizing plate. The polarizing plate includes a λ / 2 polarizer positioned outside the organic electroluminescent display and a λ / 4 retardation film positioned between the λ / 2 polarizer and the organic electroluminescent display. The light control film is characterized in that the color filter. At least one end of the color filter is formed with a black matrix to surround the color filter. The anode electrode and the cathode electrode of the organic light emitting diode included in the organic light emitting display device are formed of a transparent or translucent material.

Hereinafter, the present invention will be described in detail with reference to FIGS. 2 to 4b which are attached to a preferred embodiment for easily carrying out the present invention by those skilled in the art.

2 is a diagram illustrating an organic light emitting display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, an organic light emitting display device according to an exemplary embodiment includes a pixel unit 200, a scan driver 220, and a data driver 230.

The pixel unit 200 includes a plurality of pixels 210 including an organic light emitting diode (OLED) (not shown), and each of the pixels 210 includes scan lines S1 to Sn and data lines D1 to Dm. It is formed in the area partitioned by). The pixel unit 200 receives the first power source ELVDD and the second power source ELVSS from the outside. Each of the pixels 210 receives a scan signal, a data signal, a first power source ELVDD, and a second power source ELVSS to display an image. Here, a light control film (not shown) such as a polarizing plate or a color filter is attached to one surface of the pixel part 200 to reduce the reflection of external light to improve the contrast of the pixel part 200.

The scan driver 220 generates a scan signal. The scan signals generated by the scan driver 220 are sequentially supplied to the scan lines S1 to Sn.

The data driver 230 generates a data signal. The data signal generated by the data driver 230 is supplied to the data lines D1 to Dm to be synchronized with the scan signal and transferred to each pixel 210.

3 is a cross-sectional view illustrating a pixel of the organic light emitting display device illustrated in FIG. 2. The pixel may include an organic light emitting diode, at least one capacitor, a transistor, or the like. For convenience, only an organic light emitting diode and a transistor connected to the organic light emitting diode will be shown in FIG. 3.

Referring to FIG. 3, the pixel 210 of the organic light emitting display device illustrated in FIG. 2 includes a transistor formed on the lower substrate 310 and an organic light emitting diode 380 formed to be connected to the transistor. The light control layer 400 is attached to one surface of the 210, for example, the lower substrate 310 or the upper substrate 390 of the pixel 210.

The transistor is formed on the lower substrate 310 and includes a semiconductor layer 320 including a source and drain region 320a and a channel region 320b, a gate insulating layer 330 formed on the semiconductor layer 320, and a gate. A gate electrode 340 formed on the insulating film 330, an interlayer insulating film 350 formed on the gate electrode 340, and an interlayer insulating film 350 formed on the insulating film 330 and electrically connected to the source and drain regions 320a. Source and drain electrodes 360 are included.

The planarization layer 370 is formed on the transistor, and the organic light emitting diode 380 is formed on the planarization layer 370.

The organic light emitting diode 380 includes an anode electrode 380a formed to be connected to a transistor, a light emitting layer 380b formed on the anode electrode 380a, and a cathode electrode 380c formed on the light emitting layer 380b. . Here, the anode electrode 380a and the cathode electrode 380c of the organic light emitting diode 380 are formed of a transparent or translucent light transmitting material for double-sided light emission.

A passivation layer 385 is formed on the cathode electrode 380c, and an upper substrate 390 is formed on the passivation layer 385 to encapsulate the pixel 210.

The light control film 400 attached to the upper substrate 390 is for preventing the degradation of contrast caused by external light, and the light control film 400 includes a polarizing plate or a specific wavelength for passing only light in a specific direction. A color filter or the like that passes only light of may be used. That is, the light control layer 400 serves to suppress reflection by external light by transmitting only specific light.

In this case, when the polarizing plate is attached to the light control film 400, the polarizing plate may be composed of a λ / 4 retardation film 400a and a λ / 2 polarizer 400b as shown in FIG. 4A. have. In this case, the λ / 2 polarizer 400b is attached to the outside and the λ / 4 retardation film 400a is positioned inside. Then, only a part of the light incident from the outside passes through the λ / 2 polarizer 400b. Then, the light transmitted through the λ / 2 polarizer 400b is incident on the λ / 4 retardation film 400a which gives a phase difference of 1/4 wavelength. When the light incident on the λ / 4 retardation film 400a is polarized by 45 degrees and is reflected by 45 degrees, the light is reflected by 90 degrees and is not polarized. Therefore, the amount of light emitted from the light emitting layer to the outside is also reduced to about 60% of the original amount of light emission, but the reflection of the external light is suppressed, thereby improving the contrast. Such a polarizing plate is easily applied to subpixels emitting light of different colors in the same manner. In addition, an anti-reflection (AR) coating may be applied to the surface of the polarizer to reduce surface reflection without damaging the focus state of the pixel portion.

Meanwhile, as shown in FIG. 4B, a color filter may be attached instead of the polarizing plate to be used as the light control layer 400. In this case, when a color filter having the same color as that of each subpixel is attached in consideration of the color of light emitted from each subpixel, the light emitted from the light emitting layer to the outside may pass through the color filter well. In addition, the light incident to the pixel from the outside is significantly reduced while passing through the color filter, thereby reducing the reflected light. Here, a black matrix (BM) may be formed at the end of each color filter to surround the color filter, thereby further increasing contrast.

As such, when the light control film 400 is attached to one surface of the pixel, the brightness of the surface on which the light control film 400 is attached is relatively low, but contrast reduction that may be caused by external light may be prevented. Therefore, when the image is viewed from one surface of the pixels to which the light control film 400 is attached in the outdoor with strong external light, the image of high contrast can be viewed.

On the other hand, in a room where external light is not strong, it is more efficient not to attach the light control film 400 to display an image of high brightness. Accordingly, the organic light emitting diode display according to the present invention is preferably a double-sided light emitting organic light emitting diode display that emits light on both the surface to which the light control film 400 is attached and the surface to which the light control film 400 is not attached. That is, indoors where the light control film 400 is not attached are used. To this end, the anode electrode 380a and the cathode electrode 380c of the organic light emitting diode OLED included in each pixel are formed of a transparent or semitransparent material.

As described above, since both the anode electrode 380a and the cathode electrode 380c of the organic light emitting diode 380 are transparently formed of a light-transmissive material, the pixel can emit light on both sides. Further, by attaching the light control film 400 to one surface of the double-sided light emitting pixel, the surface on which the light control film 400 is attached is prevented from lowering contrast due to external light, and thus can be usefully used outdoors. The surface to which the 400 is not attached may be usefully used indoors by displaying an image of high brightness.

Although the technical spirit of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various modifications are possible within the scope of the technical idea of the present invention.

As described above, according to the organic light emitting diode display and a method of manufacturing the same, by attaching a light control film to one surface of the pixel portion for emitting both sides, an image having improved contrast can be displayed outdoors with strong external light. In addition, since the light control film is not attached to the other surface of the pixel portion, the image of the high brightness can be displayed and be usefully used indoors.

Claims (7)

In an organic light emitting display device in which light extraction is formed on a lower substrate and an upper substrate, On one surface of the organic light emitting display device is provided with a light control film for controlling light extraction, The light control film includes a lambda / 2 polarizer positioned outside the organic electroluminescent display, and a lambda / 4 retardation film positioned between the lambda / 2 polarizer and the organic electroluminescent display. An organic light emitting display device, characterized in that the polarizing plate. delete delete The method of claim 1, The amount of light extracted through the polarizing plate is within 60% of the amount of light generated from the light emitting layer of the organic light emitting display device. delete delete According to claim 1, And an anode electrode and a cathode electrode of the organic light emitting diode included in the organic light emitting display device are formed of a transparent or translucent material.

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