KR20130027914A - Method for fabricating retardatiion film and organic light emitting display device using the same - Google Patents

Abstract

PURPOSE: A method for fabricating a retardation film and an organic light emitting display device using the same are provided to remove the reflection luminance of external light. CONSTITUTION: A lower substrate(100) is formed in a pixel region of a white color organic light emitting layer. A red(R), a green(G), a blue(B), and a white(W) color filter are formed in an upper substrate(110). Each region corresponding to each color filter is formed on a retardation film(120). A polarization plate(130) is formed on the phase difference film. A sub layer(150) is formed between the retardation film and the upper substrate.

Description

Method for fabricating Retardatiion film and Organic light emitting display device using the same}

The present invention relates to a retardation film manufacturing method and an organic light emitting display device using the same.

Recently, studies are being actively conducted to increase the display quality of a flat panel display device and attempt to make a large screen. Among these, the electroluminescent display device is a self-luminous element that emits light by itself. The electroluminescent display displays a video image by exciting a fluorescent material using carriers such as electrons and holes. The electroluminescent display is largely divided into an inorganic electroluminescent display and an organic electroluminescent display according to the material used. The organic electroluminescent display is driven at a lower voltage of about 5 to 20 volts than the inorganic electroluminescent display requiring a high voltage of 100 to 200 volts, thereby allowing direct current low voltage driving.

In addition, the organic electroluminescent display has excellent features such as wide viewing angle, high speed response, high contrast ratio, and the like, such as pixels of graphic displays, television image displays or surface light sources. It is suitable as next-generation flat panel display because it can be used as a thin, light and good color.

On the other hand, the driving method of the organic light emitting display device is divided into a passive matrix type (passive matrix type) that does not have a separate thin film transistor, and an active matrix type electroluminescent display device having a thin film transistor.

Recently, an active matrix type electroluminescent display device for manufacturing next-generation displays requiring high resolution and a large screen has been used.

In addition, in the past, red (R), green (G), and blue (B) color organic light emitting layers were formed in subpixel units of the organic light emitting display device, and red, green, and blue subpixels were used as unit pixels. The red (R), green (G), and blue (B) organic light emitting layers are laminated on the subpixels, and a white (W) color organic light emitting layer is used.

FIG. 1 is a view schematically illustrating a structure of an organic light emitting display device according to the prior art, and FIG. 2 is a view comparing an optical axis of a polarizing plate and an optical axis of a conventional retardation film.

1 and 2, an organic light emitting display device includes a lower substrate 10 having a white organic light emitting layer and red (R), green (G), blue (B), and white (W) color filters. An upper substrate 20 having a color filter layer C / F formed thereon is bonded to each other, and a retardation film 30 and a polarizer 40 are attached to the rear surface of the upper substrate 20.

The retardation film 30 phases the linearly polarized external light by λ / 2 when external light is linearly polarized by the polarizer 40 and then reflected by the lower substrate 10 through the color filter layer C / F. By delaying the function to block the polarizing plate 400.

That is, the optical axis θr of the retardation film 30 and the optical axis θp of the polarizing plate 40 are designed to form an angle of 45 °, but the retardation film 30 has a phase difference of λ / 4 so that external light Is delayed by λ / 4 as it is incident, reflected by the lower substrate 10, and delayed by λ / 4, thereby delaying phase by λ / 2.

As a result, since external light is incident on the organic light emitting display device, the reflected light is reflected and blocked by the polarizing plate 40, thereby reducing the luminance of reflection and improving screen quality.

However, the conventional retardation film 30 is formed with the same thickness on the entire surface corresponding to the color filter layer (C / F), by the wavelength band of light transmitted through the red (R), green (G) and blue (B) color filter It does not properly block the reflected brightness.

 3 is a graph showing a spectrum of transmission wavelengths of a typical red, green, and blue color filter. As shown, wavelengths of light passing through the red (R), green (G), and blue (B) color filters are different from each other. You can see something else.

For example, the red (R) color filter absorbs the wavelength bands of the green (G) and blue (B) light and transmits only the light of the red wavelength band.

That is, since the wavelengths of light passing through the red (R), green (G), and blue (B) color filters are different, the phase difference (retardation) value (Δn) × distance (d) accordingly must also be adjusted.

The retardation film of the prior art has a problem in that the entire region is formed with the same thickness and has the same retardation delay value, so that the reflected light for each wavelength band cannot be properly blocked.

According to the present invention, the thickness of the region corresponding to the red (R), green (G), blue (B), and white (W) color filters of the organic light emitting display device is determined by using a photoreactive material having a change in refractive index for each wavelength band. It is an object of the present invention to provide a method for manufacturing a phase difference film in which reflection luminance of external light for each wavelength band is removed and an organic light emitting display device using the same.

In addition, the present invention, the reflection luminance of the external light using a phase difference film having a phase retardation value different from each other in the regions corresponding to the red (R), green (G), blue (B) and white (W) color filter Another object of the present invention is to provide a method for manufacturing a retardation film, and an organic light emitting display device using the same.

Retardation film manufacturing method of the present invention for solving the problems of the prior art as described above, the step of forming a first pattern using a roller on a TAC (Tri-acetyl-cellulose) film (TAC); Forming a stepped region by forming a second pattern on the TAC film on which the first pattern is formed; And forming a phase difference film having a different thickness from a photoreactive material in which photo-alignment and photosensitive materials are mixed on the TAC films on which the first and second patterns are formed.

In addition, the organic light emitting display device according to the present invention comprises: a lower substrate having a white organic light emitting layer formed in each pixel area; An upper substrate on which the red (R), green (G), blue (B) and white (W) color filters are formed; A retardation film formed on the rear surface of the upper substrate to have different thicknesses in areas corresponding to the red (R), green (G), blue (B), and white (W) color filters; And a polarizing plate formed on the retardation film, wherein an auxiliary layer made of an isotropic material is formed in the stepped area between the retardation film and the rear surface of the upper substrate.

According to an embodiment of the present invention, a thickness of a region corresponding to a red (R), green (G), blue (B), and white (W) color filter of an organic light emitting display device is determined using a photoreactive material having a change in refractive index for each wavelength band. Differently, the reflection luminance of the external light for each wavelength band is removed.

In addition, the present invention, the reflection luminance of the external light using a phase difference film having a phase retardation value different from each other in the regions corresponding to the red (R), green (G), blue (B) and white (W) color filter Has the effect of removing.

1 is a view schematically illustrating a structure of an organic light emitting display device according to the prior art.
2 is a view comparing the optical axis of the polarizing plate and the optical axis of the retardation film generally used.
3 are graphs showing spectra of transmission wavelengths of typical red, green, and blue color filters.
Figure 4 is a graph showing the refractive index distribution for each wavelength band of the photoreactive material used in the retardation film of the present invention.
5 is a view schematically illustrating a structure of an organic light emitting display device according to the present invention.
6A through 6D are graphs illustrating reflection luminances of red, green, blue, and white pixel areas of the organic light emitting display device of the present invention.
7 is a view comparing reflection luminance for each pixel area of an organic light emitting display device according to the related art.
8 is a view showing a manufacturing process of a retardation film having a phase retardation value different from each other according to the thickness according to the present invention.

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.

Figure 4 is a graph showing the refractive index distribution by wavelength band of the photoreactive material used in the retardation film of the present invention, as shown, the photoreactive material is formed by mixing a photo-alignment and a photosensitive material, the linearly polarized light It may be a liquid crystalline polymer or a low molecule or an oligomer or a mixture thereof having a photosensitive group capable of exhibiting optical anisotropy and a mesogen forming group exhibiting liquid crystallinity in a specific temperature range by irradiation.

In addition, the photo-alignment and photosensitive material is characterized in that the photo-isomerization occurs when the linearly polarized light is irradiated to form a very small optical anisotropy, and can further increase the optical anisotropy through heat treatment above a certain temperature.

In addition, the photo-alignment and photosensitive material may be azobenzene, cinnamate, coumarin, and benzylidenephthalimidine as a photoreactor, preferably a cinnamate group may be used.

When the retardation film is formed using the photoreactive material having the above characteristics, as shown in the figure, it can be seen that the refractive index (Δn) having a different wavelength for each wavelength band.

In order to minimize the reflected luminance, the condition of λ = (Δn) × (d) must be satisfied.

Therefore, in the present invention, the refractive index (Δn) and the thickness of the retardation film (d) so that the light passing through the red (R), green (G), blue (B), and white (W) color filters have different light wavelengths correspond to each other. ), The light reflected from the lower substrate of the organic light emitting display device and transmitted through the color filter is perpendicular to the optical axis of the polarizer for each wavelength band (the phase difference of λ / 2) to remove the reflected luminance of the external light.

That is, in the present invention, a retardation film is formed of a photoreactive material, and the thicknesses of the retardation films corresponding to the red (R), green (G), blue (B), and white (W) color filters are different from each other. The phase difference delay value (retardation) was set. The retardation delay value is a function of the refractive index [Delta] n and the thickness d, and when either value changes, the retardation delay value changes.

In the present invention, a retardation film is formed of a photoreactive material, and a proper retardation delay is made for each wavelength band by varying thicknesses of regions corresponding to color filters of the organic light emitting display device.

5 is a diagram schematically illustrating a structure of an organic light emitting display device according to an exemplary embodiment of the present invention, and FIGS. 6a to 6d illustrate reflection luminances of red, green, blue, and white pixel regions of an organic light emitting display device of the present invention. The graphs shown.

5 and 6A to 6D, the organic light emitting display device of the present invention includes a lower substrate 100 having a white organic light emitting layer, and red (R), green (G), blue (B), and white (W). An upper substrate 120 having a color filter layer C / F formed of color filters is bonded to each other, and a retardation film 120 and a polarizer 130 having different thicknesses are attached to the rear surface of the upper substrate 110.

An auxiliary layer 150 made of an isotropic material is formed in an area where a step is formed to control the thickness of the retardation film 120. The retardation film 120 manufacturing method of the present invention as described above will be described in detail with reference to FIG.

The retardation film 120 may be formed of the photoreactive material described with reference to FIG. 4, and the thicknesses of the retardation film 120 may be different for each wavelength band of light passing through the red (R), green (G), blue (B), and white (W) color filters. Formed differently.

As shown in FIGS. 6A to 6D, the retardation film 120 of the present invention has different refractive index (Δn) values for each wavelength band, and red (R), green (G), blue (B), and white ( W) The thickness of the retardation film is shown to have the minimum reflection luminance for each pixel region.

That is, the light passing through the green (G) and white (W) color filters has a minimum reflection luminance when the thickness of the retardation film 120 of the present invention is 1.3 μm, and the light passing through the red (R) color filter. When the thickness of the retardation film 120 is 1.4㎛, has a minimum reflection brightness, the light passing through the blue (B) color filter has a minimum reflection brightness when the thickness of the retardation film 120 is 1.2㎛ can see.

Therefore, in the retardation film 120 of the present invention, the thickness corresponding to the red (R) color filter (red pixel region) is 1.4 μm, and the thickness corresponding to the blue (B) color filter (blue pixel region) is 1.2. It is formed in a micrometer, the thickness corresponding to the green (G) and white (W) color filters (green and white pixel region) is formed to 1.3㎛.

As described above, in the present invention, the thicknesses of the pixel regions are different to correspond to the wavelengths of the light passing through the red (R), green (G), blue (B), and white (W) color filters, respectively, in order to realize the minimum reflection luminance. The retardation film of was used.

The present invention forms a retardation film using a photoreactive material of which the refractive index of each wavelength band is changed, and the retardation film regions corresponding to the red (R), green (G), blue (B), and white (W) color filters are separated from each other. Formed to a different thickness has the effect of minimizing the reflected brightness of the external light.

In addition, the present invention, by forming a retardation film having a phase retardation value different from each other in the regions corresponding to the red (R), green (G), blue (B) and white (W) color filters, the reflection luminance of the external light Has the effect of removing.

FIG. 7 is a view comparing reflection luminance of each pixel area of the organic light emitting display device according to the related art and the prior art, and as shown in the related art, red (R), green (G), blue (B), and white light in the prior art. (W) A retardation film having a uniform thickness was used regardless of the color filter, and the luminance of the reflected light passing through the blue (B) color filter was found to be the lowest.

As in the present invention, red (R), green (G), and blue (R), green (G), blue (B), and white (W) pixels of different thicknesses are used for each of the red, red (R), green (G), and blue regions. When the retardation film is formed to have different phase difference delay values for each of the (B) and white (W) pixel areas, the luminance of each pixel area may be lower than that of the prior art.

In the case of using a retardation film having a retardation delay value corresponding to an optical wavelength passing through each pixel region as in the present invention, the reflection luminance is reduced for all color filters, so that the contrast ratio (CR) is improved. Can be.

8 is a view showing a manufacturing process of a retardation film having a phase retardation value different from each other according to the thickness according to the present invention.

As shown in FIG. 8, various methods may be used to form retardation films having different thicknesses for each of red, green, blue, and white pixel regions of the organic light emitting display device. Applicable

A roller 500 is formed on a tri-acetyl-cellulose (TAC) film to form a first pattern 400 made of a predetermined isotropic material by a roll printing process, and the first pattern ( The second pattern 401 is stacked on the TAC film TAC on which 400 is formed to form different steps.

As described above, when a step is formed on the TAC film (TAC) by the first and second patterns 400 and 401, the phase difference film 410 is formed on the front surface of the TAC film by using the photoreactive material described with reference to FIG. 4. Form.

Since the first and second patterns 400 and 401 are formed of an isotropic material, the optical path difference does not occur, but the thickness of the retardation film 401 is formed by stacking the first pattern 400 and the second pattern 401. Are formed differently.

As such, when the retardation film is formed to have different thicknesses, the retardation delay value may be adjusted, and the retardation delay value may be constantly adjusted according to the light wavelength passing through the retardation film.

100: first substrate C / F: color filter layer
110: upper substrate 120: retardation film
150: auxiliary layer 130: polarizing plate
500: roller

Claims (8)

Forming a first pattern on a tri-acetyl-cellulose (TAC) film using a roller;
Forming a stepped region by forming a second pattern on the TAC film on which the first pattern is formed; And
And forming a retardation film having a different thickness from a photoreactive material in which photo-alignment and photosensitive materials are mixed on the TAC films on which the first and second patterns are formed.
The method according to claim 1, wherein the photoreactive material is a liquid crystalline polymer or a low molecule or oligomer or a mixture thereof having a photosensitive group exhibiting optical anisotropy and a mesogen forming group exhibiting liquid crystallinity in a specific temperature range when irradiated with linearly polarized light. Retardation film production method characterized by.
The method of claim 2, wherein the photoreactive material has any one of azobenzene, cinnamate, coumarin, and benzylidenephthalimidine as a photoreactor.
The method of claim 1, wherein the retardation film has different phase retardation values according to thickness.
A lower substrate having a white organic light emitting layer formed in each pixel area;
An upper substrate on which the red (R), green (G), blue (B) and white (W) color filters are formed;
A retardation film formed on the rear surface of the upper substrate to have different thicknesses in areas corresponding to the red (R), green (G), blue (B), and white (W) color filters; And
It includes a polarizing plate formed on the retardation film,
And an auxiliary layer made of an isotropic material is formed in the stepped area between the retardation film and the back surface of the upper substrate.
The liquid crystal display of claim 5, wherein the retardation film is formed of a photoreactive material, and the photoreactive material has a photosensitive property that exhibits optical anisotropy and a mesogen former that exhibits liquid crystallinity in a specific temperature range when irradiated with linearly polarized light. An organic light emitting display device comprising a polymer, a low molecule, an oligomer or a mixture thereof.
The organic light emitting display device of claim 6, wherein the photoreactive material has any one of azobenzene, cinnamate, coumarin, and benzylidenephthalimidine as a photoreactor.
The organic light emitting display device of claim 5, wherein the retardation film has different phase retardation values according to thickness.

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