KR101868476B1 - Oled display inculding polarizer - Google Patents

Abstract

The present invention relates to a polarizing plate, and more particularly, to an organic electroluminescent display including a polarizing plate, in which visibility is deteriorated due to reflection of external light of a display using an organic electroluminescent device.
An organic electroluminescent display according to an embodiment of the present invention includes a first substrate, a display element formed on the first substrate, a second substrate formed on the upper portion of the display element, and at least one of the first and second substrates Wherein a single transmission is 44.1% or more, a polarization efficiency is 99.95% or less, and an iodide ion concentration ratio (I ₃ ^- : I ₅ ^- ) adsorbed on the base film is at least 3 And a polarizing plate formed so that the iodide ion (I ₃ ^- ) has a concentration higher than that of 5 iodine and the ion (I ₅ ^- ).
According to a preferred embodiment of the present invention, a circular polarizer having high luminance and high polarizability is attached to a display surface of an OLED display, thereby maximizing brightness enhancement as well as preventing external light reflection.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an OLED display device,

The present invention relates to a polarizing plate, and more particularly, to an organic electroluminescent display including a polarizing plate, in which visibility is deteriorated due to reflection of external light of a display using an organic electroluminescent device.

2. Description of the Related Art Flat panel display devices of recent interest include a liquid crystal display, a field emission display, a plasma display panel, and an electroluminescent display (EL) And display devices. In particular, an electroluminescent device basically has electrodes on both surfaces of an organic light emitting layer composed of a hole transporting layer, a light emitting layer, and an electron transporting layer, and is attracting attention as a next generation flat panel display device because of its wide viewing angle, high aperture ratio and high color.

Such an electroluminescent element is divided into an inorganic electroluminescent element and an organic electroluminescent element depending largely on the material used. In the dual organic electroluminescent device, when an electric charge is injected into the organic EL layer formed between the hole injection electrode and the electron injection electrode, electrons and holes are paired and then emitted, There are advantages.

In addition, the organic electroluminescent device not only can form devices on a flexible transparent substrate such as a plastic but also can be driven at a voltage as low as 10 V or less as compared with a PDP or an inorganic electroluminescent device, Is relatively small and excellent in color.

A display to which an organic electroluminescent device according to the related art having such characteristics is applied will be described with reference to FIG.

1 is a cross-sectional view illustrating an example of a conventional organic light emitting display.

The conventional organic electroluminescent display 1 includes a first substrate 2 on which an organic luminescent layer 4 is formed and a first substrate 2 which is bonded to the first substrate 2 by a sealant or the like to protect the organic luminescent layer 4 And a second substrate (8).

In the organic EL display 1 having such a structure, a polarizing plate 9 for blocking external light is further attached to the light emitting surface side where an image is viewed. When the display of FIG. 1 displays an image in the upward direction, A polarizing plate 9 is disposed on the outer surface of the substrate 8.

The polarizing plate 9 includes the lambda / 4 retardation layer 9a and the linear polarization layer 9b. In the conventional organic EL display device 1, when the display device 1 is driven in an external environment, The polarizing plate 9 is adhered to the outside of the display surface in order to prevent it.

The polarizing plate 9 is formed such that light emitted from the organic light emitting layer 4 is incident on the display 1 to be linearly polarized through the linear polarized light layer 9b and right circularly polarized through the? / 4 retardation layer 9a, The retardation layer 9a and the linearly polarized light layer 9b are reflected by the reflective layer 8 or the reflection plate (not shown) provided thereon and are reflected by the left circularly polarized light and the linearly polarized light, The polarizing plate 9 can not transmit.

Therefore, in the OLED display 1, the polarizing plate 9 composed of the? / 4 retardation layer 9a and the linear polarization layer 9b is formed on the outer surface of the first substrate 2 or the second substrate 8 Thereby blocking the light from the outside, thereby improving the contrast characteristic.

However, such an organic electroluminescent device display improves the above-described external light characteristics by applying a high-brightness polarizing plate. However, since polarization and light transmittance of light are inversely proportional to each other, there are limitations in improving the characteristics thereof. .

SUMMARY OF THE INVENTION The present invention has been conceived to solve the above-mentioned problems, and it is an object of the present invention to provide an organic electroluminescent display including a polarizing plate having a high single light transmittance characteristic while maximizing a polarization degree of a polarizing plate attached to the display in order to improve visibility It has its purpose.

According to an aspect of the present invention, there is provided an organic electroluminescent display, including: a first substrate; A display element formed on the first substrate; A second substrate formed on the display device; And a second substrate attached to at least one of the first and second substrates and having a single transmission of 43% or more, a polarization efficiency of 99.99% or less, and an iodide ion concentration ratio I ₃ ^- : I ₅ ^- ) comprises at least a trivalent iodide ion (I ₃ ^- ) having a concentration greater than 5 iodine and I ₅ ^- .

The polarizing plate is characterized in that it is produced by stretching a polyvinyl alcohol (PVA) film.

Wherein the polarizer comprises a? / 4 retardation layer formed on any one of the first substrate and the second substrate; And a linear polarization layer formed on the? / 4 retardation layer.

The polarizing plate is characterized in that the polarization degree is 99.95% to 91.09% when the single light transmittance is 44.1% to 47.8%.

Wherein the polarizing plate is, when the external light is 0 lx (illuminance), a black tone (0 gray) has a ^{0.01530 cd / m 2 ~ 0.01775 cd} / m 2, white gradations (255 gray) is ^{284 cd / m 2 ~ 312 cd} / m < ^{2 &} gt ;.

The polarizing plate is characterized in that triacetyl cellulose (TAC) is further formed on the surface thereof.

The polarizing plate is characterized in that the reflectance is 5.409% to 10.708, the lightness is 28.3345 to 38.974, the first reflection color is -1.3728 to -5.3573 and the second reflection color is -6.8152 to -13.2553.

The display device includes: a thin film transistor and an anode electrode sequentially formed on the first substrate; An organic light emitting layer formed on the anode electrode; A cathode electrode formed on the organic light emitting layer; And a protective film formed on the cathode electrode.

According to a preferred embodiment of the present invention, a circular polarizer having high luminance and high polarizability is attached to a display surface of an OLED display, thereby maximizing brightness enhancement as well as preventing external light reflection.

1 is a cross-sectional view of an example of a conventional organic light emitting diode display.
2 is a cross-sectional view of an organic electroluminescent display including a polarizing plate according to the present invention.

Hereinafter, an organic electroluminescent display including a polarizing plate according to a preferred embodiment of the present invention will be described with reference to the drawings.

2 is a cross-sectional view of an organic electroluminescent display including a polarizing plate according to the present invention.

2, the organic light emitting display 10 according to the embodiment of the present invention includes a thin film transistor 34 for driving a pixel on a first substrate 20, a thin film transistor 34 An anode electrode 36 is formed on the anode electrode 36, and an organic light emitting layer 38 is formed on the anode electrode 36.

A cathode electrode 40 is formed on the organic light emitting layer 38 and a protective film 42 is formed on the cathode electrode 40.

In detail, a semiconductor layer 44 is formed on the first substrate 20, and a gate insulating film 50 and a gate electrode 52 are sequentially deposited thereon and patterned. The thin film transistor portion 34 on the substrate 20 is formed with the semiconductor layer 44 and the source and drain regions 48 of the thin film transistor 34 and the electrode lines 56 through the contact holes.

A first interlayer insulating film 54, a planarization film 58 and an anode electrode 36 are sequentially formed on the gate electrode 52. An anode electrode (not shown) is formed between the gate insulating film 50 and the first interlayer insulating film 54, 36 and the source and drain regions 48 of the thin film transistor are formed.

A second interlayer insulating film 60 is formed on the anode electrode 36 to cover a part between the anode electrodes 36. Above the second interlayer insulating film 60 are formed a hole injecting portion and a hole injecting portion, And an organic light emitting layer 38 on which an electron injecting portion is sequentially deposited.

A cathode electrode 40 is formed on the organic light emitting layer 38 and the protection unit 42 formed on the cathode electrode 40 includes a protection film 72 and a shield cap 74.

Although not shown, the side surface of the organic electroluminescent device 10 is closely adhered to the upper surface of the organic electroluminescent device 10 by a protective film 72, which is an adhesive, and a shield cap 74. The shield cap 74 may be formed of an encapsulant for molding the lower structure or may be omitted by replacing the glass substrate and the second substrate 80 made of a material so as to face the upper substrate 20. [

A polarizing plate 90 is disposed above the second substrate 80 to pass through without loss from the second substrate 80 and absorb light incident from the outside to further increase the visualization of the image. The polarizing plate 90 is attached to the light emitting surface of the organic light emitting diode display 10 and may be attached to the lower surface of the first substrate 20 when the light emitting surface of the organic light emitting have.

This polarizing plate 90 is formed by laminating a polyvinyl alcohol (PVA) based resin film by dyeing and uniaxial stretching by adsorption of a dichroic dye to form a? / 4 retardation layer 92 in which the dichroic dye is oriented, 94), and may be formed in the form of a cellulose acetate-based polarizing protective film (not shown) laminated on one surface or both surfaces thereof. Here, the protective film is preferably triacetyl cellulose (TAC).

An anthraquinone, an azo dye, or iodine may be used as the dichroic dye. Particularly, in the case of iodine, a polarizer can be prepared by dyeing in an aqueous iodine solution while uniaxially stretching a polyvinyl alcohol (PVA) Followed by drying or rinsing through a color correction process using potassium iodide or the like.

In particular, the polarizing plate 90 of the present invention is attached to any one surface of the first and second substrates constituting the OLED display corresponding to the light emitting surface. The iodine which is dyed on the polyvinyl alcohol film and constitutes the linear polarization layer 94 is composed of three iodide ions (I ₃ ^- ) and five iodide ions (I ₅ ^- ).

The ion concentration ratio (I ₃ ^- : I ₅ ^- ) of iodine described above is such that at least a triiodide ion (I ₃ ^- ) is composed of a larger concentration than the pentiodiodide ion (I ₅ ^- ), And polarization characteristics.

This characteristic is caused by the characteristic of light absorbed by the iodine substance depending on the concentration ratio of each iodide ion. As the amount of the iodide ion (I ₃ ^- ) increases, the transmission increases and the concentration of the iodide ion (I ₅ ^- ) Is decreased, the polarization degree is lowered.

Therefore, the polarizer used in the organic electroluminescent device display of the present invention is manufactured such that the triiodide ion (I ₃ ^- ) has a concentration larger than the ₅ ^- iodide ion (I ₅ ^- ) (I ₃ ^- > I ₅ ^- A single transmission of 44.1% or more, and a polarization efficiency of 99.95% or less.

According to this feature, the iodide ions are three-iodide ion of polarizer (I ₃ ^-) 5 iodide ions (I ₅ ^-) was prepared to three of the polarizer a different concentration ratios in the range having a larger concentration than that, this organic electroluminescent The results of evaluating the characteristics of each display attached to the device panel are as follows.

First, white gradation, black gradation and Ambient Contrast Ratio (ACR) evaluation result data by illuminance (lx) of external light are summarized in Table 1 below. In Table 1, the unit of the luminance value according to each embodiment is cd / m ² .

Luminance (lx) 0 200 1000 2000 10000 20000 30000 Example 1 WHITE 281.4 285.3 297.7 313.1 436.1 590.0 743.1 BLACK 0.016 3.073 15.28 30.73 154.1 309.0 464.0 ACR 17590 92.8 19.5 10.2 2.83 1.91 1.60 Example 2 WHITE 296.7 301.2 314.6 331.7 468.3 639.1 810.5 BLACK 0.017 3.402 16.96 33.98 171.0 341.9 514.7 ACR 17450 88.5 18.5 9.76 2.74 1.87 1.57 Example 3 WHITE 309.8 315.5 332.4 354.3 525.1 740.6 955.6 BLACK 0.017 4.305 21.32 42.63 214.1 430.3 644.3 ACR 18220 73.3 15.6 8.31 2.45 1.72 1.48

The minimum gradation (0 gray) and the maximum gradation (255 gray) under the conditions of the dark room (0 lx) and the fluorescent lamp (200 lx) were compared with the brightness of the OLED display to which the polarizing plate was attached, ) The evaluation result data are summarized in Table 2 below.

darkroom Bright room (fluorescent lamp) Black White CR Black White CR Example 1 0.01530 284 18562 0.23214 285 1227 Example 2 0.01580 299 18924 0.36340 299 823 Example 3 0.01775 312 17577 0.46133 312 676

As shown in Table 2, the organic EL display of the present invention has a black gradation (0 gray) of 0.01530 cd / m ² to 0.01775 cd / m ² when the external light is 0 lx (illuminance) 255 gray) is 284 cd / m ² to 312 cd / m ² .

Here, it is understood that the white gradation in the dark room has a luminance increasing effect of 5 to 10% in accordance with the concentration ratio, and the luminance characteristic of the black gradation increases in the bright room due to the decrease in the degree of polarization. Accordingly, the concentration ratio of the iodide ion _{^{(I 3 -: I 5 -}} ) (- >> I 5 - I 3) 5 O to which iodide ions are formed from a too low level with respect to the undesirable.

Table 3 shows the evaluation result data of the light reflection characteristic of the OLED display to which each polarizing plate having different concentration ratios are attached.

Bulk transmittance / polarization degree (%) Reflectance Y (%) brightness Reflection color a Reflection color b Example 1 44.1% / 99.95% 5.409 28.3345 -1.3725 -6.8152 Example 2 45.9% / 97.36% 6.799 31.549 -2.9427 -10.6545 Example 3 47.8% / 91.09% 10.708 38.974 -5.3573 -13.2553

As shown in Table 3, the organic EL display of the present invention has a reflectance of 5.409% to 10.708, a lightness of 28.3345 to 38.974, a first reflection color of -1.3728 to -5.3573 and a second reflection color of -6.8152 ~ 13.2553.

In particular, it can be seen that the reflectance increases with the polarization degree of 91.09%. Under such conditions, the brightness increases and the image has a bluish tendency, and it is preferable that at least the circular polarizer is formed so as to have a characteristic larger than 91.09%.

Accordingly, the organic electroluminescent display device including the polarizing plate according to the embodiment of the present invention improves the visibility of the external light by the polarizing plate having the high single polarization transmittance characteristic while maximizing the polarization degree on the light emitting surface.

In addition, in the case of a bottom emission organic electroluminescent display having separate R, G, B, and W color filters applied to a large TV or the like, although not shown in the drawing, And therefore the polarizing plate of the present invention should be attached to the back surface of the display, i.e., the outer surface of the lower substrate.

Further, in the case of a flexible type display capable of being warped, by attaching a plurality of polymer layers on a display element and a polarizing plate according to an embodiment of the present invention on top of the scratch prevention film on the display element, The same effects as those of the first embodiment can be obtained.

It is to be noted that the technical spirit of the present invention has been specifically described in accordance with the above preferred embodiment, but it should be noted that the above-mentioned embodiments are intended to be illustrative and not restrictive. 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 and scope of the invention.

10: organic electroluminescent display 20: first substrate
34: Thin film transistor 36: Anode electrode
38: organic light emitting layer 40: cathode electrode
42: protective film 44: semiconductor layer
48: source and drain regions 50: gate insulating film
52: gate electrode 54: first interlayer insulating film
56: electrode line 58: planarization film
60: second interlayer insulating film 72: protective film
74: shield cap 80: second substrate
90: polarizer 92:? / 4 retardation layer
94: linear polarization layer

Claims (8)

A display element disposed on the first substrate and including sequentially stacked anode electrodes, an organic light emitting layer, a cathode electrode, a protective film, and a shield cap;
A second substrate positioned on the display element; And
And a polarizing plate positioned on the second substrate and having a single transmission of 43% or more and a polarization efficiency of 99.99%
Wherein the protective film comprises a pressure-sensitive adhesive,
The polarizing plate includes a? / 4 retardation layer and a linear polarization layer positioned on the? / 4 retardation layer, wherein light incident from the outside is linearly polarized through the linear polarization layer and circularly polarized through the? / 4 retardation layer ,
The? / 4 retardation layer comprises a polyvinyl alcohol (PVA) based resin film which is uniaxially stretched and in which a dichroic dye is oriented,
Wherein the linear polarized light layer comprises a base film on which triiodide ion (I ₃ ^- ) and pentad iodide ion (I ₅ ^- ) are adsorbed,
Wherein the concentration of the triiodide ion (I ₃ ^- ) adsorbed on the base film is greater than the concentration of the iodide ion (I ₅ ^- ) adsorbed on the base film. The method according to claim 1,
The dichroic dye may be,
Wherein the organic electroluminescent device comprises iodine. delete The method according to claim 1,
The polarizing plate includes:
And the polarization degree is 99.95% to 91.09% when the unit transmittance is 44.1% to 47.8%. The method according to claim 1,
The polarizing plate includes:
The black gradation (0 gray) is 0.01530 cd / m ² to 0.01775 cd / m ² and the white gradation (255 gray) is 284 cd / m ² to 312 cd / m ² when the external light is 0 lx (illuminance) Wherein the organic electroluminescent device is a display device. The method according to claim 1,
The polarizing plate includes:
Wherein a triacetyl cellulose (TAC) is further formed on a surface of the organic EL device. The method according to claim 1,
The polarizing plate includes:
Wherein the reflectance is 5.409% to 10.708%, the lightness is 28.3345 to 38.974, the first reflection color is -1.3728 to -5.3573 and the second reflection color is -6.8152 to -13.2553. delete

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