JP2007035550A - Base plate for electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EL element base plate, having a light scattering layer of high light extraction efficiency, which is less likely to be influenced by external light and has display quality of high contrast and high luminance. <P>SOLUTION: The EL element base plate is constituted of a transparent base plate and a light scattering layer formed on the transparent base plate and made of transparent resin in which particles are scattered. The average diameter of the particles is to be in the range of 1.0 to 1.6 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electroluminescent element substrate used in, for example, an electroluminescent display device.

An electroluminescence (hereinafter abbreviated as EL) element utilizes the principle that a fluorescent substance or the like emits light by recombination energy between holes injected from an anode and electrons injected from a cathode when an electric field is applied. Self-luminous element. The EL element can emit surface light with high luminance of several thousand cd / m ² or more at a low voltage of several volts, and by appropriately selecting an organic compound or the like used for the light emitting layer or the like, from blue to red It has a feature that light emission of an arbitrary wavelength is possible. Since this EL element is a self-luminous element, it has a wide viewing angle and can respond at a high speed of less than μs. Therefore, active research and development has recently been conducted as a display device that can be changed to a liquid crystal display device or a plasma display. ing.

As an example of a basic structure of a conventional EL element, a structure in which a transparent electrode, a light emitting layer, and a back electrode are stacked on a transparent substrate can be exemplified. Usually, a metal electrode having reflection characteristics is used for the back electrode, and among the light emitted from the light emitting layer, the light emitted to the rear side (metal electrode side) of the light emitting layer is reflected by the metal electrode and forward Since it radiates | emits to (transparent electrode side), there exists an advantage that the brightness | luminance of an element improves.
However, since this metal electrode also reflects light incident on the element from the outside, there is a problem that reflection by external light occurs from a region that should not be displayed (non-light emitting), and display contrast is lowered. In particular, in a portable display device used in a bright environment such as outdoors, such reflection of external light becomes a problem.

In order to suppress such a decrease in contrast due to reflection of external light, a circularly polarizing plate is generally provided on the front surface of the transparent substrate (see, for example, Patent Document 1). When a circularly polarizing plate is used, since the rotation direction of circularly polarized light is reversed when the external light is reflected by the metal electrode, the reflection of the external light can be efficiently suppressed and a high contrast display can be obtained. It is done.
However, since light emitted from the light emitting layer in the EL element is generally non-polarized light, when a circularly polarizing plate is used to prevent reflection of external light, about half of the emitted light is absorbed by the circularly polarizing plate. For this reason, there is a problem that the efficiency of taking out emitted light to the outside is reduced, and the luminance is reduced to half or less.

  Further, in the EL element, light having an incident angle greater than the critical angle determined by the refractive index of the transparent substrate and the refractive index of the output medium (for example, air) out of the light emitted from the light emitting layer is converted into the transparent substrate and the output medium. There is a problem that the light extraction efficiency is lowered because the light is totally reflected at the interface with the light-emitting layer and is confined inside the light emitting layer and cannot be extracted outside.

  Providing a light scattering layer has been proposed as a method for improving the light extraction efficiency (see, for example, Patent Documents 2 to 4). In the organic EL element having the above-described configuration, for example, when a light scattering layer is formed between the transparent substrate and the light emitting layer, the light scattering layer also guides light having an incident angle greater than the critical angle to the emission medium (for example, air). Will be. For this reason, the light extraction efficiency can be improved by forming the light scattering layer.

  The light scattering layer in Patent Documents 2 to 4 described above is one in which fine particles are dispersed in the layer. As the light scattering layer, those having characteristics that can reduce the backscattering and change the transmission angle of light efficiently are preferable. For example, in Patent Documents 2 to 4, the characteristics of the fine particles, the refractive index difference between the fine particles and the matrix, Optical design is performed according to the dispersion state, the formation position of the light scattering layer, and the like.

  However, in order to obtain a light scattering effect, for example, if the thickness of the light scattering layer is increased or the content of fine particles is increased, the total light transmittance is decreased, and as a result, the luminance is decreased. is there. For this reason, the optical design based on the characteristics of the fine particles, the refractive index difference between the fine particles and the matrix, the dispersed state of the fine particles, the formation position of the light scattering layer, etc. It is difficult to obtain a light scattering layer that satisfies the characteristics and display quality.

Japanese Patent Laid-Open No. 8-322138 JP-A-6-347617 Japanese Patent Laid-Open No. 6-151061 JP 2004-39388 A

  The present invention has been made in view of the above-described problems, and is for an EL element having a light scattering layer that is not easily affected by external light, has excellent display quality such as high contrast and high luminance, and has high light extraction efficiency. The main purpose is to provide a substrate.

  As a result of intensive studies in view of the above circumstances, the present inventors have required an optical design of the light scattering layer in order to suppress reflection of outside light without using a circularly polarizing plate, and an indicator of the light scattering effect The haze value greatly depends on the average particle size of the fine particles, and the optimum average particle size of the fine particles exists to obtain the light scattering effect in consideration of contrast, brightness, etc. Completed.

  That is, the present invention has a transparent substrate and a light scattering layer formed on the transparent substrate and having fine particles dispersed in a transparent resin, and the average particle size of the fine particles is 1.0 μm to 1.6 μm. The substrate for an EL element is provided.

  According to the present invention, the haze value can be increased by setting the average particle size of the fine particles used in the light scattering layer within a predetermined range. Therefore, when the EL element substrate of the present invention is used for an EL display device. In this case, it is possible to improve the contrast by suppressing the reflection of external light and to improve the light extraction efficiency by suppressing the total reflection of light emission at the interface between the transparent substrate and the output medium.

  In the present invention, a colored layer may be further formed on the transparent substrate, and the light scattering layer and the colored layer may be laminated in any order.

  Furthermore, in the present invention, the light shielding portion may be formed in a pattern on the transparent substrate, and in this case, the contrast can be further improved.

  The EL element substrate of the present invention preferably has a haze value in the range of 30 to 95. This is because if the haze value is smaller than the above range, a sufficient light scattering effect may not be obtained.

  In the present invention, the haze value can be increased by setting the average particle diameter of the fine particles used in the light scattering layer within a predetermined range. Therefore, when the EL element substrate of the present invention is used in an EL display device. In addition, it is possible to realize display with high contrast and high brightness.

Hereinafter, the EL element substrate of the present invention will be described in detail.
The EL element substrate of the present invention has a transparent substrate and a light scattering layer formed on the transparent substrate, in which fine particles are dispersed in a transparent resin, and the average particle size of the fine particles is 1.0 μm to It is characterized by being in the range of 1.6 μm.

Here, it is generally known that the particle size of the fine particles greatly affects the optical design of the light scattering layer, and specifically, the scattering state varies depending on the particle size d of the fine particles. That is,
(1) When the particle size d is larger than the light wavelength λ (d> λ), the region becomes a geometric optical region, geometric optical refraction and scattering due to reflection occur, and there is no wavelength dependency.
(2) When the particle diameter d is close to the light wavelength λ (λ / 3 <d <λ), it becomes a diffraction scattering region (Mie scattering), and scattering due to geometric optical scattering and diffraction effect (light interference) occurs. And has a complicated wavelength dependency. For this reason, coloring due to scattering occurs.
(3) When the particle diameter d is smaller than the light wavelength λ (d <λ / 3), it becomes a Rayleigh scattering region, scattering due to interaction with atoms / molecules occurs, and the scattering is almost uniformly performed in all directions. For this reason, not only forward scattering but also back scattering occurs.

  When the EL element substrate of the present invention is used in an EL display device, the reflection of external light is suppressed to improve contrast, and the total reflection of light emission at the interface between the transparent substrate and the emission medium (for example, air) is suppressed. In order to improve the light extraction efficiency, omnidirectional scattering is not preferable. Therefore, it is preferable that the particle diameter of the fine particles corresponds to the case (1) or (2) having excellent forward scattering characteristics among the above. Furthermore, in order to prevent coloring due to scattering, the particle diameter of the fine particles is preferably in the geometric optical region (1).

  Moreover, in order to make the intensity of the scattered light by the light scattering layer sufficient, it is necessary to increase the haze value [haze value = (diffuse light transmittance) / (total light transmittance) × 100]. In particular, in an EL display device, a higher haze value is required. This is because, for example, external light is sometimes used as a light source in a liquid crystal display device. In this case, reflected light is actively used for display, whereas an EL element is a self-luminous element. This is because it is preferable to suppress reflection of external light in order to improve display quality. If the haze value is higher, reflection of external light can be effectively suppressed, and total reflection of light emission at the interface between the transparent substrate and the emission medium (for example, air) can also be effectively suppressed.

In order to enable a high haze value (high dustiness), it is necessary to increase the content of fine particles and increase the thickness of the light scattering layer. At this time, the total light transmittance and diffuse light transmittance are increased. It is not preferable that the decrease. For example, when titanium oxide or calcium carbonate known as general fine particles is used for the light scattering layer, the haze value is increased by increasing the content of the fine particles or increasing the thickness of the light scattering layer. However, on the other hand, the light shielding property of the fine particles is developed, and the total light transmittance is remarkably lowered.
In contrast, in the present invention, by setting the average particle size of the fine particles used in the light scattering layer within a predetermined range, it is possible to increase the haze value while suppressing a decrease in the total light transmittance and the diffuse light transmittance. It is.

  Furthermore, in the present invention, by setting the average particle size of the fine particles used in the light scattering layer within a predetermined range, reflection of external light can be suppressed as described above without using a circularly polarizing plate. When used in a display device, light emission from the light-emitting layer can be used effectively, and luminance can be improved.

The EL element substrate of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of an EL element substrate of the present invention. As illustrated in FIG. 1, an EL element substrate 10 of the present invention includes a transparent substrate 1 and a light scattering layer 2 formed thereon. The light scattering layer 2 is configured by dispersing fine particles having a predetermined average particle diameter in a transparent resin.

In the present invention, a colored layer may be formed on the light scattering layer. For example, as shown in FIG. 2A, a colored layer 3 may be formed between the transparent substrate 1 and the light scattering layer 2. Usually, the colored layer 3 includes a red colored pattern 3R, a green colored pattern 3G, and a blue colored pattern 3B.
As described above, depending on the particle size of the fine particles in the light scattering layer, the light scattering layer may be colored due to scattering. Even in such a case, when the colored layer is formed, the color characteristic of the light scattering layer can be reliably compensated for by correcting the color characteristic of the colored layer. Can be suppressed.

Furthermore, in this invention, the light-shielding part may be formed on the transparent substrate. This light-shielding part is provided to shield the peripheral edge of the panel of the EL display device, to align the colored patterns of the EL element substrate, or to shield between the colored patterns.
Hereafter, each structure of the board | substrate for EL elements of this invention is demonstrated.

1. Light Scattering Layer The light scattering layer used in the present invention is sufficient to cause appropriate scattering in light emitted from the light emitting layer in the EL display device when the EL element substrate of the present invention is used in, for example, an EL display device. In order to ensure high visibility, fine particles having a predetermined average particle diameter and having a light scattering action are dispersed in a transparent resin.

  The average particle size of the fine particles used in the present invention is in the range of 1.0 μm to 1.6 μm, preferably 1.0 μm to 1.4 μm, more preferably 1.2 μm to 1.4 μm. . This is because when the average particle size is in the above range, a high haze value can be achieved and excellent light scattering characteristics can be obtained. In addition, if the average particle diameter is in the above range, a uniform film thickness distribution can be achieved by application with a normal spinner, and a relatively thin light scattering layer having excellent patterning characteristics can be formed. It is.

  Here, the average particle diameter is generally used to indicate the particle size of the particles, and in the present invention, is a value measured by a laser method. The laser method is a method of measuring an average particle size, a particle size distribution, and the like by dispersing particles in a solvent and thinning and calculating scattered light obtained by applying a laser beam to the dispersion solvent. The average particle size is a value measured using a particle size analyzer Microtrac UPA Model-9230 manufactured by Leeds & Northrup as a particle size measuring device by a laser method.

  The fine particles used in the present invention are not particularly limited as long as they have a light scattering action. For example, inorganic substances such as silicon oxide, aluminum oxide, barium sulfate, acrylic resins, divinylbenzene resins, benzoguanamine series Resin, styrene resin, melamine resin, acrylic-styrene resin, polycarbonate resin, polyethylene resin, polyvinyl chloride resin, and other organic materials, or a mixture of two or more of these fine particles. it can.

  The fine particles preferably have transparency. This is because the total light transmittance and the diffuse light transmittance can be improved. As such fine particles, among the above, melamine resins, benzoguanamine resins, polymethyl methacrylate resins, mixed resins and copolymers thereof are preferably used. These fine particles also have durability.

  Furthermore, the shape of the fine particles is not particularly limited, but is preferably spherical.

  In the present invention, the refractive index of the fine particles is preferably larger than the refractive index of the transparent resin described later. Generally, in order to develop light scattering characteristics, the difference in refractive index between the fine particles and the transparent resin is used, and ideally, the refractive index of the transparent resin is set to be larger than the refractive index of the fine particles. It is preferable. However, considering the difference in refractive index between the fine particles and the transparent resin and considering the coloring of the light scattering layer, it is preferable to set the refractive index of the fine particles to be larger than the refractive index of the transparent resin.

  Since the refractive index of a transparent resin to be described later is generally about 1.5, the refractive index of the fine particles is preferably larger than 1.5. Examples of such fine particles include aluminum oxide (1.62), benzoguanamine / formaldehyde condensate (1.66), benzoquamine / melamine / formaldehyde condensates (1.66, 1.52), and melamine / formaldehyde condensates ( 1.66), silica / acrylic compound (1.52), methacrylic compound (1.51) and the like. The numbers in parentheses indicate the refractive index.

  The content of the fine particles in the light scattering layer is not particularly limited as long as it is an amount that can scatter light and does not impair the transparency of the light scattering layer. It can be set at about 5 to 70% by weight, preferably 1.0 to 50% by weight. If the content of fine particles is too small, the light scattering effect may not be obtained, and if the content of fine particles is too large, it may be difficult to maintain the transparency and strength of the light scattering layer. is there.

  The transparent resin used in the present invention is appropriately selected in consideration of the difference in refractive index from the fine particles, the transparency of the light scattering layer, the adhesion to the transparent substrate and the colored layer, and the like. Examples of the transparent resin include acrylic resins, epoxy resins, polyvinyl alcohol resins, polyimide resins, vinyl ether resins, and the like. These transparent resins can be used alone or as a mixture of two or more.

  The total light transmittance of the light scattering layer used in the present invention is preferably 80% or more, more preferably 85% or more, and most preferably 90% or more. This is because if the total light transmittance is too small, the luminance may decrease when the EL element substrate of the present invention is used in an EL display device.

  Moreover, it is preferable that the haze value of a light-scattering layer is about 30-95, More preferably, it exists in the range of 50-95, Most preferably, it exists in the range of 60-90. This is because if the haze value is smaller than the above range, a sufficient light scattering effect may not be obtained.

  In addition, said total light transmittance and haze value are the values measured with the direct reading haze meter by Toyo Seiki Seisakusho Co., Ltd. using the integrating sphere.

  The light scattering layer may be formed on the entire surface of the transparent substrate, or may be formed in a pattern. Further, the patterned light scattering layer may be formed according to the pattern of the light emitting layer in the EL display device, and when a colored layer described later is formed, it is formed according to the colored pattern of the colored layer. It may be.

  The light scattering layer used in the present invention can be formed by applying and solidifying a light scattering layer forming coating solution containing fine particles and a transparent resin. In this case, the light scattering layer forming coating solution is preferably an ultraviolet curable resist, and more preferably a negative ultraviolet curable resist. This is because, if the coating solution for forming the light scattering layer is an ultraviolet curable resist, it can be easily patterned by, for example, exposure through a photomask.

  At this time, the ultraviolet curable resist used contains an ultraviolet curable binder resin, a photopolymerization initiator, and the like. When a thick light scattering layer is formed by containing a large amount of this ultraviolet curable binder resin or photopolymerization initiator in an ultraviolet curable resist, the light scattering layer may be colored. For this reason, the thickness of the light scattering layer is preferably relatively thin.

  The thickness of the light scattering layer is not particularly limited as long as it does not impair the transparency, and is usually about 0.5 μm to 20 μm, preferably 1.0 μm to 5 μm. Further, from the viewpoint of patterning, the range of 1.5 μm to 6.5 μm is preferable. This is because, when the thickness of the light scattering layer is thinner than the above range, the resist component that controls the adhesion to the transparent substrate is reduced, and an uneven surface is formed. At this time, if the thickness of the light scattering layer is too thin, each fine particle is developed and a desired pattern may not be obtained. On the other hand, if the light scattering layer is too thick, it may be difficult to maintain transparency. In particular, if the thickness of the light scattering layer is greater than 6.5 μm, when ultraviolet light exposure is used, the light does not reach the lower part of the light scattering layer, so that it is unexposed and patterning characteristics may not be obtained. .

2. Transparent substrate The transparent substrate used in the present invention is not particularly limited as long as it can be generally used in an EL display device. For example, inflexible transparent rigid materials such as quartz glass, Pyrex (registered trademark) glass, and synthetic quartz plates, or transparent flexible materials having flexibility such as transparent resin films and optical resin plates may be used. it can. Among these, Corn 2000 Eagle 2000 or 1737 glass is a material having a small coefficient of thermal expansion, excellent dimensional stability and workability in high-temperature heat treatment, and is a non-alkali glass containing no alkali component in the glass. Are preferably used. In particular, the present invention is suitable when the EL element substrate of the present invention is applied to an active display type EL display device.

3. Colored layer In the present invention, a colored layer may be further formed on the transparent substrate. The colored layer 3 may be formed between the transparent substrate 1 and the light scattering layer 2 as shown in FIG. 2 (a), for example, on the light scattering layer 2 as shown in FIG. 2 (b), for example. It may be formed.
When a colored layer is formed between the transparent substrate and the light scattering layer, the transparent substrate surface is flatter than the light scattering layer, and therefore it is easy to form and pattern the colored layer. There are advantages. In addition, since the colored layer for correcting the color characteristics is provided on the light exit surface side than the light scattering layer, even if the light scattering layer is colored, the color change can be suppressed. it can. Furthermore, since the light scattering layer can be formed without being exposed to the heat process (post-bake) when forming the colored layer, it is possible to avoid yellowing of the transparent resin in the light scattering layer due to heat.
On the other hand, when the colored layer is formed on the light scattering layer, the colored layer is formed via the light scattering layer, and therefore the light scattering layer increases the adhesion between the transparent substrate and the colored layer. can do.

  The colored layer used in the present invention is composed of a plurality of colored patterns. The multi-color coloring pattern is generally composed of a red coloring pattern, a green coloring pattern, and a blue coloring pattern. The arrangement of the coloring pattern is not particularly limited, and examples thereof include a stripe type, a mosaic type, a triangle type, and a four pixel arrangement type.

  When the light shielding part mentioned later is not formed between such coloring patterns, it is preferable that the coloring patterns are formed without gaps. This is because the contrast can be improved.

  As a material for forming the colored layer, materials generally used for color filters can be applied, and examples thereof include organic pigments and inorganic pigments.

  Further, the thickness of the colored layer is not particularly limited, but is preferably a thickness capable of correcting colored characteristics of the light scattering layer. For example, the colored characteristics of the light scattering layer can be corrected by making the thickness of the colored layer relatively thin. In this case, the thickness of the colored layer is appropriately adjusted according to the target color characteristic correction.

  The colored layer can be formed by a general pigment dispersion method, dyeing method, electrodeposition method or the like. In the case of forming a colored layer by a pigment dispersion method, a pigment dispersion resist in which the above-described organic pigment or inorganic pigment is dispersed is used as a colored layer forming coating solution.

  In order to form a colored pattern with high accuracy, an alignment mark is preferably formed. The alignment mark is usually formed simultaneously with the formation of the first color pattern. When a light shielding portion described later is formed at a predetermined position, this light shielding portion can be used as an alignment mark.

4). Light Shielding Part In the present invention, for example, as shown in FIG. 3, the light shielding part 5 may be formed in a pattern on the transparent substrate 1. The light shielding portion shields light between the patterns of the light emitting layer in the EL display device, or shields the peripheral edge of the panel of the EL display device, or when the colored layer is formed, the colored pattern of the colored layer In order to shield the gap or to align the colored pattern, etc., it is provided, and the contrast can be further improved.

  Furthermore, the said light-shielding part should just be formed on the transparent substrate, and may be formed in either the side in which the light-scattering layer of the transparent substrate is formed, or the side in which the light-scattering layer is not formed. .

  The light shielding part used in the present invention can be formed of a light shielding resin, a metal such as chromium, for example.

5. Flattened layer In the present invention, in order to eliminate the fine irregularities on the surface of the light scattering layer and form a flat surface, and when the colored layer is formed, the fine irregularities on the surface of the colored layer are eliminated. In order to form a flat surface, or to form a flat surface by eliminating irregularities due to each colored pattern of the colored layer, even if a planarizing layer is formed on the light scattering layer or the colored layer Good.

In particular, when an EL display device is manufactured using the EL element substrate of the present invention, for example, when a transparent electrode layer or the like is formed on a light scattering layer in the EL element substrate, the planarizing layer is formed. It is preferable that Since the light scattering layer contains fine particles, fine irregularities are likely to occur on the surface, and it may be difficult to form a uniform transparent electrode layer, but by the formation of a planarizing layer on the light scattering layer, This is because a uniform transparent electrode layer can be formed.
In addition, when a colored layer is formed on the light scattering layer, it is possible to planarize fine irregularities on the surface of the light scattering layer by providing a planarizing layer between the light scattering layer and the colored layer. This is because the patterning characteristics of the colored layer are improved. Furthermore, in this case, since the planarizing layer is formed on the colored layer, a uniform transparent electrode layer can be formed as in the above case. In addition, when the colored layer is formed, a short circuit may occur between the electrodes when irregularities due to the colored patterns of the colored layer are reflected on the transparent electrode layer, but the planarized layer is formed. The short circuit between the electrodes can be prevented.

  On the other hand, for example, in the case where an EL display device is manufactured by separately manufacturing and bonding an EL element substrate and a counter substrate, the planarization layer may not be formed.

  The flattening layer is formed on the light scattering layer when only the light scattering layer is formed on the transparent substrate, but when the colored layer is formed, the light scattering layer and Regardless of the order of lamination of the colored layers, the light scattering layer and the colored layer may be formed on top of each other, or may be formed between the light scattering layer and the colored layer.

  The planarization layer used in the present invention can be formed using, for example, an acrylic resin, an epoxy resin, a vinyl ether resin, a polyimide resin, a propynyl resin, or the like.

6). Gas Barrier Layer In the present invention, a gas barrier layer may be formed on the light scattering layer. Since the light emitting layer and other organic layers in the EL display device are weak members against oxygen, water vapor, and other gases, the generation of dark spots and dark areas can be suppressed by providing a gas barrier layer. It is. In particular, when the colored layer is formed, a gas may be generated from the colored layer or the like during manufacture or driving of an EL display device. Can be prevented from deteriorating.

  As the gas barrier layer, those generally used as a gas barrier layer of an EL display device can be used. For example, silicon oxide, silicon nitride, silicon oxynitride or the like is used.

7). Transparent electrode layer In the present invention, a transparent electrode layer may be formed on the light scattering layer. The transparent electrode layer is formed on the light scattering layer when only the light scattering layer is formed on the transparent substrate, but when the colored layer is formed, the light scattering layer and the colored layer are formed. Layers are formed on top of each other.

  As the transparent electrode layer used in the present invention, for example, indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO), or an alloy thereof is used. The transparent electrode layer can be formed by a general film forming method such as a sputtering method, a vacuum vapor deposition method, a CVD method or the like.

  The thickness of the transparent electrode layer can be set to about 0.01 μm to 1 μm, and preferably about 0.03 μm to 0.5 μm.

8). Others The haze value of the EL element substrate of the present invention is preferably about 30 to 95, more preferably in the range of 50 to 95, and most preferably in the range of 60 to 90. This is because if the haze value is smaller than the above range, a sufficient light scattering effect may not be obtained. From the viewpoint of front luminance, the upper limit of the haze value is preferably 95.

  Further, the total light transmittance of the EL device substrate of the present invention is preferably 80% or more, more preferably 85% or more, and most preferably 90% or more. This is because if the total light transmittance is too small, the luminance may decrease when the EL element substrate of the present invention is used in an EL display device.

  The haze value, total light transmittance, and diffuse light transmittance are values measured using a direct reading haze meter manufactured by Toyo Seiki Seisakusho.

  The EL element substrate of the present invention can be applied to a self-luminous display device such as an EL display device, a plasma display (PDP), or a field emission display (FED). By using the EL element substrate of the present invention, a display with high contrast and high luminance can be obtained. Among these, the EL element substrate of the present invention is preferably applied to an EL display device. In this case, the EL element substrate of the present invention can be applied to both an organic EL display device and an inorganic EL display device.

  In particular, the EL element substrate of the present invention is suitably used for an active drive type EL display device. This is because the EL element substrate of the present invention can suppress reflection of external light and is suitable for a display device used for a digital still camera or a digital video movie used in an external environment. In general, since a digital still camera, a digital video movie, or the like has a megapixel resolution, a resolution is also required for a display device that displays the resolution. A passive drive display device cannot obtain high resolution due to its configuration, and high-definition display devices have generally shifted to an active drive method. Further, regarding the display colors of colors, an active drive type display device capable of controlling an intermediate color with a thin film transistor (TFT) element can reproduce many display colors.

FIG. 4 shows an example of an EL display device using the EL element substrate of the present invention. 4A illustrates an example of a bottom emission EL display device, and FIG. 4B illustrates an example of a top emission EL display device.
For example, in the EL display device 30 shown in FIG. 4A, the transparent electrode layer 12, the light emitting layer 11, and the metal electrode layer 13 are formed on the EL element substrate 10, and the substrate 15 is formed thereon. Yes. A partition wall 16 is formed between the light emitting layers 11, and the transparent electrode layer 12 is formed together with a thin film transistor (TFT) 17.
For example, in the EL display device 30 shown in FIG. 4B, the EL element substrate 10 and the metal electrode layer 13, the light emitting layer 11, the transparent electrode layer 12, and the refractive index matching layer 14 are formed on the substrate 15. The counter substrate 20 is laminated. A partition wall 16 is formed between the light emitting layers 11, and the metal electrode layer 13 is formed together with a thin film transistor (TFT) 17.
Since the EL element substrate of the present invention suppresses reflection of external light and suppresses total reflection of light emission at the interface between the transparent substrate and the emission medium, the light extraction surface of any EL display device The EL element substrate is disposed on the side.

  Among bottom emission and top emission, top emission is advantageous in that the ratio of the light emitting portion (light emission area ratio) is large. This is because, in bottom emission, the TFT circuit is formed on the light extraction surface side, so the light emission area is reduced. In top emission, light is extracted from the surface opposite to the TFT circuit formation surface. This is because even if a complicated TFT circuit is formed, the light emitting area is not affected.

The EL element substrate of the present invention uses, for example, an EL display device using a light emitting layer that emits white light, an EL display device that uses light emitting layers that emit three primary colors, and a light emitting layer that emits blue light. The present invention can be applied to any EL display device that displays the three primary colors by conversion.
When the EL element substrate of the present invention has a transparent substrate and a light scattering layer, it is preferably used for an EL display device using light emitting layers that emit light of the three primary colors. On the other hand, when the EL element substrate of the present invention has a transparent substrate, a light scattering layer, and a colored layer, it is preferably used in an EL display device using a light emitting layer that emits white light.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

Hereinafter, the present invention will be specifically described with reference to examples.
[Example 1]
As the substrate, a 0.7 mm thick glass substrate (Corning 1737 glass) was prepared. On this glass substrate, a coating solution for forming a light scattering layer having the following composition is applied and dried, followed by exposure, development, and post-baking (200 ° C., 30 minutes) to obtain a light scattering layer (thickness). 6 μm) was formed.

(Light scattering layer coating solution)
・ Acrylic resin (Nippon Kayaku Co., Ltd., KAYARAD PET.30) 50 parts by weight ・ Melamine resin beads 10 parts by weight ・ Polymerization initiator (Ciba Specialty Chemicals, Irgacure 184) 4 parts by weight ・ Dilution Solvent (polyethylene glycol monoethyl acetate) 36 parts by weight The average particle diameter of the melamine-based resin beads was changed within a range of 0.8 μm to 2.3 μm.

  The haze value of the EL element substrate thus obtained was measured with a direct reading haze meter manufactured by Toyo Seiki Seisakusho. The results are shown in Table 1 below.

  As apparent from Table 1, a high haze value was obtained when the average particle diameter of the melamine resin beads was 1.0 to 1.6 μm.

[Example 2]
As a substrate, a 0.7 mm thick glass substrate (Corning Corp., 1737 glass) was prepared. On this glass substrate, a photosensitive coloring material for red coloring pattern (Fuji Film Orin Co., Ltd., color mosaic CR-7000) is applied by spin coating, and the coating film is exposed through a predetermined photomask. Then, it developed using the developing solution (Fuji Film Orin Co., Ltd. product, CD), hold | maintained the glass substrate for 30 minutes at 200 degreeC, the colored layer was hardened, and the red colored pattern was formed.
Similarly, photosensitive coloring material for green coloring pattern (Fuji Film Olin Co., Ltd., color mosaic CG-7000) and blue coloring pattern photosensitive coloring material (Fuji Film Olin Co., Ltd., color mosaic CB-) 7000), a green colored pattern and a blue colored pattern were formed in the same manner as described above to obtain a colored layer. In the formation of the colored layer, the thickness of the coating film of the photosensitive coloring material is set to 50 to 80% of the conventional value in order to correct the colored characteristics of the light scattering layer.
Next, a light scattering layer (thickness 6 μm) was formed on the colored layer in the same manner as in Example 1.

  The haze value of the EL element substrate thus obtained was measured with a direct reading haze meter manufactured by Toyo Seiki Seisakusho. The results are shown in Table 1 above. Similar to Example 1, a high haze value was obtained when the average particle diameter of the melamine resin beads was 1.0 to 1.6 μm.

[Example 3]
As the substrate, a 0.7 mm thick glass substrate (Corning Corp., 1737 glass) was prepared. On this glass substrate, a photosensitive coloring material for red coloring pattern (Fuji Film Orin Co., Ltd., color mosaic CR-7000) is applied by spin coating, and the coating film is exposed through a predetermined photomask. Then, it developed using the developing solution (Fuji Film Orin Co., Ltd. product, CD), hold | maintained the glass substrate for 30 minutes at 200 degreeC, the colored layer was hardened, and the red colored pattern was formed.

  Similarly, photosensitive coloring material for green coloring pattern (Fuji Film Olin Co., Ltd., color mosaic CG-7000) and blue coloring pattern photosensitive coloring material (Fuji Film Olin Co., Ltd., color mosaic CB-) 7000), a green colored pattern and a blue colored pattern were formed in the same manner as described above to obtain a colored layer. In the formation of the colored layer, the thickness of the coating film of the photosensitive coloring material is set to 50 to 80% of the conventional value in order to correct the colored characteristics of the light scattering layer.

  Next, a coating solution for forming a light scattering layer having the following composition is applied onto the colored layer by a spin coating method and dried, followed by exposure, development, and post-baking (200 ° C., 30 minutes). (Thickness 6 μm) was formed.

(Light scattering layer coating solution)
・ Acrylic resin (Nippon Kayaku Co., Ltd., KAYARAD PET.30) 50 parts by weight ・ Melamine resin beads 10 parts by weight ・ Polymerization initiator (Ciba Specialty Chemicals, Irgacure 184) 4 parts by weight ・ Dilution Solvent (polyethylene glycol monoethyl acetate) 36 parts by weight The average particle size of the melamine-based resin beads was changed within the range of 1.4 μm to 2.3 μm.

The haze value of the EL element substrate thus obtained was measured with a direct reading haze meter manufactured by Toyo Seiki Seisakusho.
Further, the EL device substrate was subjected to variable angle reflection spectroscopy measurement using a variable angle photometer manufactured by Murakami Color Research Laboratory. In variable reflection spectroscopy, a matching oil is applied on a Cr reflector, an evaluation sample is placed thereon, the light receiving part is 40 °, the incident part is ± 30 ° with respect to regular reflection, and the measurement pitch is set. Every 2 °. As an evaluation sample, a circularly polarizing plate was used as a comparison in addition to the EL element substrate. Further, only the Cr reflector was measured. In the measurement of the EL element substrate, the reflector / light scattering layer / colored layer / glass substrate is arranged, and in the measurement of the circularly polarizing plate, the reflector / glass substrate / circularly polarized light. It arranged so that it might become a board.
The results are shown in Table 2 below.

  From Table 2, it was found that when the haze value of the EL element substrate was 50 or more, performance equivalent to that of a circularly polarizing plate (regular reflection suppression performance) was obtained.

[Example 4]
As the substrate, a 0.7 mm thick glass substrate (Corning 1737 glass) was prepared. On this glass substrate, a coating solution for forming a light scattering layer having the following composition is applied and dried, followed by exposure, development, and post-baking (200 ° C., 30 minutes) to obtain a light scattering layer (thickness). 6 μm) was formed.

(Light scattering layer coating solution)
・ Acrylic resin (Nippon Kayaku Co., Ltd., KAYARAD PET.30) 50 parts by weight ・ Melamine resin beads 10 parts by weight ・ Polymerization initiator (Ciba Specialty Chemicals, Irgacure 184) 4 parts by weight ・ Dilution Solvent (polyethylene glycol monoethyl acetate) 36 parts by weight The average particle diameter of the melamine-based resin beads was changed within a range of 0.8 μm to 1.4 μm.

  The haze value of the light scattering layer thus obtained was measured with a direct reading haze meter manufactured by Toyo Seiki Seisakusho. Further, the total light transmittance of the light scattering layer was measured using an integrating sphere. As a comparison, the total light transmittance of the circularly polarizing plate was also measured. The results are shown in Table 3 below.

  From Table 3, it was found that the light scattering layer had a total light transmittance exceeding that of the circularly polarizing plate even when the haze value was high.

It is a schematic sectional drawing which shows an example of the board | substrate for EL elements of this invention. It is a schematic sectional drawing which shows the other example of the board | substrate for EL elements of this invention. It is a schematic sectional drawing which shows the other example of the board | substrate for EL elements of this invention. It is a schematic sectional drawing which shows an example of the EL display apparatus using the board | substrate for EL elements of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transparent substrate 2 ... Light-scattering layer 3 ... Colored layer 5 ... Light-shielding part 10 ... EL element substrate

Claims (4)

  It has a transparent substrate and a light scattering layer formed on the transparent substrate, in which fine particles are dispersed in a transparent resin, and the average particle size of the fine particles is in the range of 1.0 μm to 1.6 μm. A substrate for an electroluminescence element.   The electroluminescent device substrate according to claim 1, wherein a colored layer is further formed on the transparent substrate, and the light scattering layer and the colored layer are laminated in any order.   The electroluminescent element substrate according to claim 1, wherein a light shielding portion is formed in a pattern on the transparent substrate.   The haze value is in a range of 30 to 95, and the substrate for an electroluminescent element according to any one of claims 1 to 3.

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