KR20150078391A - Organic light emitting diode display device - Google Patents

Abstract

An organic electroluminescent display device is disclosed. The disclosed organic electroluminescent display device of the present invention comprises: an organic light emitting element for emitting light by being formed on a substrate; a dual brightness enhancement film (DBEF) formed on the organic light emitting element; a cholesteric liquid crystal (CLC) film formed on the DBEF; a phase delay plate formed on the CLC film; and a polarizing plate formed on the phase delay plate. Therefore, the organic electroluminescent display device in accordance with the present invention can favorably realize black by removing the reflection of external light and improve the contrast. Moreover, the present invention is capable of enhancing the efficiency as it is possible to release light as much as possible without forming light absorbed by the polarizing plate, reducing power consumption and improving a life cycle of the element.

Description

[0001] The present invention relates to an organic light emitting diode display device,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting display device, and more particularly, to an organic light emitting display device including a polarizing plate that prevents light incident from the outside from being emitted to the outside, thereby improving device efficiency.

In recent years, as the information age has come to a full-fledged information age, a display field for visually expressing electrical information signals has been rapidly developed. In response to this, various flat panel display devices having excellent performance of thinning, light weight, Flat Display Device) has been developed to replace CRT (Cathode Ray Tube).

Specific examples of such flat panel display devices include a liquid crystal display device (LCD), an organic light emitting display (OLED), an electrophoretic display (EPD) A plasma display panel (PDP), a field emission display (FED), an electroluminescence display (ELD), and an electro-wetting display (EWD) And the like. In general, a flat panel display panel, which realizes images, is an essential component. The flat panel display panel includes a pair of substrates bonded together with an intrinsic light emitting material or a polarizing material layer therebetween.

Since an organic light emitting diode (OLED) display device, which is one of such flat panel display devices, includes an organic light emitting element that is a self light emitting element, a separate light source used in a liquid crystal display It is lightweight and thin. In addition, it has superior viewing angle and contrast ratio compared with liquid crystal display devices, is advantageous in terms of power consumption, can be driven by DC low voltage, has a quick response speed, is resistant to external impacts due to its solid internal components, It has advantages.

The organic light emitting diode is a device for emitting light by depositing an organic light emitting layer formed of an organic material between an anode made of ITO or the like and a cathode made of aluminum or the like on a glass substrate and applying an electric field. When a voltage is applied between the anode and the cathode of the organic light emitting diode, holes are injected from the anode, electrons are injected from the cathode, and then excitons are generated in the light emitting layer through migration. The organic light emitting display may use light emitted when the generated excitons fall to a ground state.

At this time, the conventional organic light emitting display device includes at least one electrode capable of reflecting light, and has a problem of reflecting light incident from the outside. Therefore, it is difficult to realize black due to reflection of external light, and the contrast is lowered.

In order to solve such a problem, there is a configuration in which a polarizing plate and a phase delay plate are disposed to suppress reflection of external light. However, it is difficult to completely block the external light. In this case, when the polarizing plate and the phase delay plate are disposed to suppress reflection of external light, a considerable part of the light generated in the organic light emitting layer is lost together.

An object of the present invention is to provide an organic light emitting display device capable of eliminating reflection of external light, capable of satisfactorily implementing black, and capable of improving contrast.

It is another object of the present invention to provide an organic electroluminescent display device capable of emitting light to the maximum extent without forming light absorbed in a polarizing plate, thereby improving efficiency, reducing power consumption, and improving lifetime of a device. .

According to an aspect of the present invention, there is provided an organic light emitting display including: an organic light emitting device formed on a substrate and emitting light; A dual brightness enhancement film (DBEF) formed on the organic light emitting device; A cholesteric liquid crystal (CLC) film formed on the reflective polarizing film; A phase delay plate formed on the cholesteric liquid crystal film; And a polarizing plate formed on the phase delay plate.

INDUSTRIAL APPLICABILITY The organic electroluminescent display device according to the present invention can eliminate the reflection of external light, can achieve good black, and has a first effect of improving contrast.

The organic electroluminescent display device according to the present invention can improve the efficiency, reduce the power consumption, and improve the lifetime of the device by emitting light to the maximum without forming the light absorbed in the polarizing plate. It is effective.

1 is a view illustrating an organic light emitting display device according to the present invention.
FIG. 2 is a view showing paths of light emitted from the outside and light emitted from the organic light emitting device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

1 is a view illustrating an organic light emitting display device according to the present invention.

Referring to FIG. 1, an element substrate 100 of an organic light emitting display according to the present invention is divided into a display region and a non-display region, and the display region is divided into a plurality of pixel regions. A thin film transistor (TFT) is formed in each pixel region, and an organic light emitting element 200 electrically connected to the thin film transistor (TFT) is formed. A DBEF 302, a cholesteric liquid crystal (CLC) film 303, a phase retardation plate 304, and a polarizing plate (not shown) are formed on the organic light emitting device 200, 305 are sequentially stacked and formed.

The element substrate 100 is formed on the insulating substrate 10 with a semiconductor layer 11 including a source region 11a, a channel region 11b and a drain region 11c. A gate insulating film 12 is formed on the semiconductor layer 11 and a gate wiring 13 and a gate electrode 13 branched from the gate wiring are formed on the gate insulating film 12. An interlayer insulating film 14 is formed on the gate wiring and the gate electrode 13.

A source line 15 branched from the data line, and a drain electrode 16 spaced apart from the source electrode 15 by a predetermined distance. The data line 16 intersects the gate line with the interlayer insulating film 14 interposed therebetween, Is formed. The source electrode 15 and the drain electrode 16 are electrically connected to each other through the interlayer insulating film 14 formed on the gate electrode 13 and the contact hole formed through the gate insulating film 12, And is connected to the source region 11a and the drain region 11c. The thin film transistor (TFT) includes a semiconductor layer 11, a gate electrode 13, a source electrode 15, and a drain electrode 16.

A protective film 17 is formed on the source electrode 15 and the drain electrode 16 and a contact hole exposing the drain electrode 16 is formed on the protective film 17. The exposed drain electrode 16 is electrically connected to the connection electrode 18 formed on the passivation layer 17. A planarization film 19 is formed on the entire surface of the insulating substrate 10 including the thin film transistor TFT and a contact hole exposing the connection electrode 18 is formed on the planarization film 19.

An organic light emitting diode 200 electrically connected to the thin film transistor TFT is formed through a contact hole formed in the planarization layer 19. The organic light emitting device 200 includes a first electrode 20, an organic light emitting layer 22, and a second electrode 23.

More specifically, the first electrode 20 of the organic light emitting device 200 is formed on the exposed connection electrode 18. Although the first electrode 20 of the organic light emitting diode 200 and the drain electrode 16 of the thin film transistor are connected through the connection electrode 18 in the drawing, the connection electrode 18 is omitted, The first electrode 20 of the thin film transistor 200 and the drain electrode 16 of the thin film transistor may be formed in direct contact with each other through the planarizing film 19 having the contact holes.

A bank pattern 21 is formed on the first electrode 20 to expose the first electrode 20 in units of pixel regions. An organic light emitting layer 22 is formed on the exposed first electrode 20. The organic light emitting layer 22 may be formed of a single layer of a light emitting material or may include a hole injection layer, a hole transporting layer, an emitting material layer, and an electron transporting layer an electron transporting layer, and an electron injection layer.

A second electrode 23 is formed on the organic light emitting layer 22. When the first electrode 20 is an anode, the second electrode 23 is a cathode and when the first electrode 20 is a cathode, the second electrode is an anode, lt; / RTI > A protective layer 210 is formed on the second electrode 23 to protect the display elements.

The device substrate 100 and the organic light emitting diode 200 of the organic light emitting display according to the present invention are not limited thereto and various changes and modifications can be made without departing from the technical idea of the present invention.

At this time, a reflection plate 301 may be formed under the organic light emitting diode 200. That is, a reflection plate 301 may be formed between the organic light emitting diode 200 and the element substrate 100. A reflection plate 301 may be formed under the first electrode 20 of the organic light emitting diode 200. In addition, the first electrode 20 may be formed to include a reflective film. Also, the reflection plate 301 may be omitted, and the first electrode 20 or the second electrode 23 may serve as a reflection plate.

A DBEF 302, a cholesteric liquid crystal (CLC) film 303, a phase retardation plate 304, and a polarizing plate (not shown) are formed on the organic light emitting device 200, 305 are sequentially stacked and formed. The dual brightness enhancement film (DBEF) 302, the cholesteric liquid crystal (CLC) film 303, the phase retardation plate 304, and the polarizing plate 305 are formed on the organic light emitting diode 200 may be stacked on the protective layer 210 to protect the display elements of the display panel 200.

That is, a dual brightness enhancement film (DBEF) 302 is disposed on the organic light emitting device 200, and the reflective polarizing film 302 is directly disposed on the reflective polarizing film 302, A cholesteric liquid crystal (CLC) film 303 is formed. A phase retardation plate 304 is formed on the cholesteric liquid crystal film 303 so as to be in contact with each other and laminated on the phase retardation plate 304 so as to be in contact with the polarizing plate 305.

The polarizing plate 305 linearly polarizes the light. Specifically, the polarizing plate 305 transmits light that coincides with the polarization axis, and absorbs light that does not coincide with the polarization axis. That is, when light passes through the polarizing plate 305, the light is linearly polarized in the direction of the polarization axis of the polarizing plate 305.

The phase delay plate 304 may be a 1/4 wavelength plate. At this time, the phase delay plate 304 can convert linearly polarized light into circularly polarized light. The phase retardation plate 304 may be arranged such that when the linearly polarized light enters the polarization axis of the polarizing plate 305, the linearly polarized light is circularly polarized to the right. Hereinafter, the circularly polarized light to the right is referred to as right-handed circularly polarized light. Also, left circularly polarized light is referred to as left circularly polarized light.

The phase retardation plate 304 may be arranged such that when the right-handed circularly polarized light enters, the right-handed circularly polarized light is linearly polarized in the polarization axis direction of the polarizing plate 305. In addition, when the left circularly polarized light enters the phase delay plate 304, the left circularly polarized light may be arranged to be linearly polarized light in a direction different from the polarization axis of the polarizing plate 305. When the left circularly polarized light enters the phase delay plate 304, the left circularly polarized light may be linearly polarized in a direction perpendicular to the polarization axis of the polarizing plate 305.

The cholesteric liquid crystal (CLC) film 303 may selectively transmit or reflect circularly polarized light. The upper surface of the cholesteric liquid crystal film 303 reflects when the right-handed circularly polarized light is incident. At this time, the upper surface of the cholesteric liquid crystal film 303 is characterized by reversing the phase of right-handed circularly polarized light to left-handed circularly polarized light. That is, when circularly polarized light is incident on the upper surface of the cholesteric liquid crystal film 303 to the right, it is reflected by the circularly polarized light to the left.

On the other hand, the lower surface of the cholesteric liquid crystal film 303 can reflect left-handed circularly polarized light and transmit right-handed circularly polarized light. That is, the cholesteric liquid crystal film 303 has different characteristics on the upper and lower surfaces. Therefore, it is possible to have different characteristics with respect to light emitted from the inside and light entering from the outside.

When linearly polarized light is incident on the cholesteric liquid crystal film 303, the linearly polarized light passes through the cholesteric liquid crystal film 303 and can be converted into circularly polarized light. When the linearly polarized light in the polarization axis direction of the reflective polarizing film 302 is incident on the lower surface of the cholesteric liquid crystal film 303, the linearly polarized light may become right circularly polarized light while transmitting the cholesteric liquid crystal film 303.

The dual brightness enhancement film (DBEF) 302 passes light corresponding to the polarization axis and reflects light that does not coincide with the polarization axis. The reflective polarizing film 302 differs from the polarizing plate 305 in that it reflects light that does not coincide with the polarization axis.

At this time, among the light emitted from the organic light emitting diode 200, light not matching the polarization axis of the reflection type polarizing film 302 is reflected and is incident on the reflection plate 301 formed under the organic light emitting device 200 , While being reflected back toward the outside, a phase delay occurs. Thus, the light is circulated between the reflection type polarizing film 302 and the reflection plate 301, a part of the light passes through the reflection type polarizing film 302, and the remainder is reflected again. The light emitted from the reflective polarizer film 200 may be emitted to the outside as light having the same polarization axis as that of the reflective polarizer film 302.

When the first electrode 20 or the second electrode 23 of the organic light emitting diode 200 serves as a reflector, the light is reflected by the reflective polarizing film 302 and the first A part of the light is circulated between the electrode 20 and the second electrode 23, passes through the reflection type polarizing film 302, and the remainder is reflected again. Finally, the light is emitted from the organic light emitting device 200 The light can be emitted to the outside as the light coinciding with the polarization axis of the reflective polarizing film 302.

In the conventional organic light emitting display device, a structure for suppressing reflection of light introduced from the outside has been studied. However, it has a problem that it can not be removed by minimizing the reflection of external light. As a result, it is difficult to implement a completely black state and the contrast is lowered. Further, there is a problem that light emitted from the organic light emitting device is lost together with the reflection of external light.

The organic light emitting display device according to the present invention can remove the light from the outside and minimize the loss of the internal light emitted from the organic light emitting device. Hereinafter, the effect of removing the light incident from the outside and minimizing the loss of the internal light emitted from the organic light emitting device will be described with reference to the drawing showing the path of the light.

FIG. 2 is a view showing paths of light emitted from the outside and light emitted from the organic light emitting device.

Referring to FIG. 2, the light introduced into the organic light emitting display device according to the present invention from the outside can not be emitted to the outside again. The external light 400, which is light from the outside, passes through the polarizing plate 305, and is absorbed except for light in a direction coinciding with the polarization axis of the polarizing plate 305. That is, only the linearly polarized light 401 in the direction coinciding with the polarization axis of the polarizing plate 305 is incident on the polarized plate 305.

The linearly polarized light 401 is incident on the phase delay plate 304. The linearly polarized light 401 becomes the right circularly polarized light 402 and is incident on the upper surface of the cholesteric liquid crystal film 303 while passing through the phase delay plate 304. That is, when the phase delay plate 304, which is a 1/4 wave plate, is incident on the polarizing plate 305 in the direction in which the polarizing axis of the polarizing plate 305 is incident, the linearly polarized light 401 is transmitted through the right- Passes through the plate 304 and becomes the right circularly polarized light 402.

The upper surface of the cholesteric liquid crystal film 303 is reflected by the left-handed circularly polarized light 403 when the right-handed circularly polarized light 402 is incident. Therefore, the right-handed circularly polarized light 402 is reflected on the upper surface of the cholesteric liquid crystal film 303 to become the left-handed circularly polarized light 403, and is incident on the phase delay plate 304 again.

When the left circularly polarized light 403 is incident, the phase delay plate 304 transmits the linearly polarized light 404. The linearly polarized light 404 is linearly polarized light 404 in a direction different from the polarization axis of the polarizing plate 305. At this time, the linearly polarized light 404 has a direction perpendicular to the polarization axis of the polarizing plate 305.

Therefore, since the linearly polarized light 404 has a direction perpendicular to the polarization axis of the polarizing plate 305, the linearly polarized light 404 is incident on the polarizing plate 305 and then absorbed by the polarizing plate 305. Thus, the external light 400, which is the light introduced from the outside, can be removed without being discharged to the outside again. Since the external light 400 is not emitted back to the outside, the organic light emitting display according to the present invention can improve the implementation of black and the contrast.

Also, loss of light emitted from the organic light emitting diode 200 of the organic light emitting display according to the present invention can be minimized. Part of the internal light 500 emitted from the organic light emitting diode 200 passes through the reflection type polarizing film 302 and is linearly polarized light 501. The linearly polarized light 501 is linearly polarized light in the same direction as the polarization axis of the reflective polarizing film 302. The light 504 excluding the linearly polarized light 501 is reflected by the reflective polarizing film 302 and is incident on the reflection plate 301 under the organic light emitting device 200.

The light 504 reflected by the reflective polarizing film 302 circulates between the reflective plate 301 and the reflective polarizing film 302 while a part of the light passes through the reflective polarizing film 302, And the remainder is re-reflected. Therefore, the light initially reflected by the reflection type polarizing film 585 may finally become the linearly polarized light 501 while passing through the reflection type polarizing film 302. Accordingly, the light emitted from the organic light emitting diode 200 can minimize the loss, and most of the light can be emitted to the outside.

The linearly polarized light 501 passing through the reflective polarizing film 302 is incident on the lower surface of the cholesteric liquid crystal film 303. The linearly polarized light 501 is incident on the lower surface of the cholesteric liquid crystal film 303 and can be transmitted through the cholesteric liquid crystal film 303 and transmitted through the right circularly polarized light 502.

That is, when the linearly polarized light is incident on the lower surface of the cholesteric liquid crystal film 303, it can be transmitted as circularly polarized light. At this time, when the linearly polarized light 501 in the polarization axis direction of the reflective polarizing film 302 is incident on the lower surface of the cholesteric liquid crystal film 303, the linearly polarized light 501 transmits the cholesteric liquid crystal film 303 And becomes right-handed circularly polarized light 502.

The right-handed circularly polarized light 502 is incident on the phase delay plate 304. When the right circularly polarized light 502 is incident, the phase delay plate 304 transmits the linearly polarized light 503. The linearly polarized light 503 is linearly polarized light 503 in a direction coinciding with the polarization axis of the polarizing plate 305.

The light 503 emitted from the organic light emitting diode 200 having passed through the phase delay plate 304 has the same direction as the polarization axis of the polarizer 305, . That is, the internal light 500, which is the light emitted from the inside, can be emitted to the outside without being absorbed by the polarizing plate 305.

Therefore, the organic light emitting display device according to the present invention can eliminate the reflection of external light, can realize good black, improve the contrast, and does not emit light to be absorbed by the polarizing plate, The efficiency can be improved, the power consumption can be reduced, and the lifetime of the device can be improved.

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 invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100: element substrate
200: Organic light emitting device
301: reflector
302: Reflection type polarizing film
303: cholesteric liquid crystal film
304: phase delay plate
305: polarizer

Claims (9)

An organic light emitting element formed on the substrate and emitting light;
A dual brightness enhancement film (DBEF) formed on the organic light emitting device;
A cholesteric liquid crystal (CLC) film formed on the reflective polarizing film;
A phase delay plate formed on the cholesteric liquid crystal film; And
And a polarizer formed on the phase delay plate.
The method according to claim 1,
Wherein the cholesteric liquid crystal film reflects the left circularly polarized light when the right circularly polarized light is incident on the upper surface thereof.
The method according to claim 1,
The light transmitted through the polarizer and entering from the outside is linearly polarized,
Wherein the linearly polarized light passes through the phase delay plate and becomes a right circularly polarized light.
The method according to claim 1,
Wherein the phase delay plate transmits linearly polarized light in a direction perpendicular to the polarization axis of the polarizing plate when the left circularly polarized light is incident.
The method according to claim 1,
Wherein the cholesteric liquid crystal film transmits circularly polarized light when linearly polarized light enters the lower surface thereof.
6. The method of claim 5,
Wherein the cholesteric liquid crystal film transmits right circularly polarized light when linearly polarized light in the same direction as the polarization axis of the reflective polarizing film is incident on a lower surface thereof.
The method according to claim 1,
Wherein the phase retarder transmits linearly polarized light in the same direction as the polarization axis of the polarizer when the right circularly polarized light is incident.
The method according to claim 1,
And a reflective plate is further formed between the organic light emitting diode and the substrate.
9. The method of claim 8,
The light emitted from the organic light emitting element passes through the reflective polarizing film, is reflected,
Wherein the light reflected from the reflection type polarizing film is incident on the reflection plate, is reflected, and is incident on the reflection type polarizing film again.

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