Patent Application
20120064228
1. Field of the Invention
The present invention relates to a forming method of a light extracting structure which is used to allow light generated from a light-emitting layer to be easily extracted to an outside of a display surface side in order to improve a luminance of an image display apparatus for displaying an image by a light emission. The invention also relates to a manufacturing method of a light-emitting substrate having the light extracting structure and the image display apparatus.
2. Description of the Related Art
A light extracting structure is a structure in which materials having different refractive indices are periodically arranged and is ordinarily constructed by forming a fine concave/convex pattern by a photolithography step which is used in a general semiconductor microfabrication. However, when a pitch of the fine concave/convex pattern is equal to about 2 μm or less, an expensive exposing apparatus and complicated processes are necessary, so that manufacturing costs are very high.
Therefore, hitherto, as a method whereby the fine concave/convex pattern which is used as a light extracting structure can be easily formed, Japanese Patent No. 4068578 discloses the following method. That is, a particle dispersion liquid in which particles have been dispersed into a liquid dispersion medium is prepared, a capture layer containing a polymer is formed onto a substrate, and a coating film of the particle dispersion liquid is formed on the capture layer. The liquid dispersion medium is volatilized from the coating film and a sediment layer of the particles is formed on the capture layer. After that, only by heating the capture layer to a temperature which is equal to or higher than a glass transition point, only the particles in the lowest layer of the sediment layer are embedded into the capture layer by a capillary tube phenomenon. The sediment layer of the particles is dipped into the liquid and the particles which are not embedded in the capture layer are removed. A single-particle layer in which the particles in the lowest layer are arranged in the capture layer is formed, thereby forming the fine concave/convex pattern.
However, Japanese Patent No. 4068578 discloses nothing about a relation between a light extracting efficiency and a filling rate of the particles. According to the light extracting structure constructed by the fine concave/convex pattern which has merely been formed by using the method disclosed in Japanese Patent No. 4068578, there is such a problem that it is difficult to form the light extracting structure having the high light extracting efficiency.
The invention is made by finding out such a fact that the filling rate of the particles exerts a large influence on the light extracting efficiency. It is an object of the invention to enable a light extracting structure of a high light extracting efficiency to be easily obtained. It is another object of the invention to enable an image display apparatus having a high luminance to be easily manufactured.
According to an aspect of the invention, there is provided a forming method of a light extracting structure, comprising the steps of; (a) forming a capture layer onto at least either a substrate or a film made of a first translucent material, (b) applying a dispersion liquid in which particles have been dispersed into a dispersion medium onto the capture layer, volatilizing the dispersion medium, and forming a sediment layer of the particles onto the capture layer, (c) embedding the particles in a lowest layer of the sediment layer into the capture layer and capturing, (d) removing the particles which are not captured in the capture layer, (e) using the particles captured in the capture layer as a mask, removing a part of the capture layer and the substrate or the film of the first translucent material, and forming a plurality of concave portions into the substrate or the film of the first translucent material, (f) removing the particles and the capture layer after the step (e), (g) embedding the plurality of concave portions formed in the substrate or the film of the first translucent material by a second translucent material whose refractive index differs from that of the first translucent material, wherein a particle filling rate of the particles captured in the capture layer in the step (c) is equal to 93% or more for a 2-dimensional closest packing.
According to another aspect of the invention, there are provided a manufacturing method of a light-emitting substrate having a light extracting structure for extracting light generated from a light-emitting layer and a manufacturing method of an image display apparatus, wherein the light extracting structure is formed by the forming method of the light extracting structure according to the invention.
In the invention, the fine concave/convex pattern necessary as a light extracting structure is formed by arranging the particles and using them as a mask. Therefore, such a light extracting structure can be easily obtained without using the expensive exposing apparatus and complicated processes. Since the particles arranged at a high particle filling rate are used as a mask, the light extracting structure having a high light extracting efficiency can be obtained. The forming method of the light extracting structure according to the invention can be used to manufacture the light-emitting substrate having the light extracting structure and the image display apparatus. The image display apparatus of a high luminance can be easily manufactured.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
The present invention relates to a forming method of a light extracting structure for extracting light generated from a light-emitting layer, a manufacturing method of a light-emitting substrate having the light extracting structure and an image display apparatus.
According to the forming method of the light extracting structure of the invention, the light extracting structure is formed by the following steps (a) to (g). In the step (c), a particle filling rate of particles captured in a capture layer is equal to 93% or more for a 2-dimensional closest packing.
(a) The capture layer is formed onto a substrate made of a first translucent material or a film made of the first translucent material formed on the substrate.
(b) A dispersion liquid in which particles have been dispersed into a dispersion medium is applied onto the capture layer, the dispersion medium is volatilized, and a sediment layer of the particles is formed onto the capture layer.
(c) The particles in the lowest layer of the sediment layer are embedded into the capture layer and captured.
(d) The particles which are not captured in the capture layer are removed.
(e) The particles captured in the capture layer are used as a mask, a part of the capture layer and the substrate or the film made of the first translucent material are removed, and a plurality of concave portions are formed in the substrate or the film of the first translucent material.
(f) After the step (e), the particles and the capture layer are removed.
(g) The plurality of concave portions formed in the substrate or the film of the first translucent material are embedded with a second translucent material whose refractive index differs from that of the first translucent material.
The exemplary embodiments of a manufacturing method of the invention will be described hereinbelow with reference to the drawings. However, the invention is not limited to the embodiments, which will be described hereinbelow.
As image display apparatuses which are manufactured by using the invention, besides a field emission display (FED), an electroluminescence display (EL), a cathode ray tube display (CRT), a light emitting diode display (LED), a plasma display (PDP), and the like can be mentioned. Among them, the invention can be desirably applied to the FED and EL in which it is desirable to provide a light extracting structure in order to improve a luminance. The embodiments of the invention will be specifically described hereinbelow with respect to the FED as an example.
The m scanning wirings 32 are connected to terminals Dx1, Dx2, . . . , and Dxm, respectively. The n modulation wirings 33 are connected to terminals Dy1, Dy2, and Dyn, respectively (m and n are positive integers). Interlayer insulating layers (not illustrated) are arranged between the m scanning wirings 32 and the n modulation wirings 33, thereby electrically insulating them.
A high-voltage terminal is connected to the anode electrode 13. A DC voltage of, for example, a few kV is supplied to this terminal. Such a DC voltage is an accelerating voltage for applying such an enough energy that an electron which is emitted from the electron-emitting device 34 excites phosphor. The electrons which were emitted from the electron-emitting device 34 and accelerated are irradiated to the phosphor film 18 so as to emit the light, thereby displaying an image.
A construction of the face plate 10 serving as a component element of the image display apparatus in
The light extracting structure 12 to extract the light generated by the light emission of the phosphor film 18 to the substrate 11 side is formed on the substrate 11 constructing the face plate 10. As a substrate 11, for example, a substrate of floating glass such as soda lime glass, no-alkali glass, or the like can be used. The anode electrode 13 formed by a transparent electrode such as ITO or the like is formed on the substrate 11. The phosphor film 18 containing a number of phosphor particles is formed on the anode electrode 13. The phosphor film 18 may be partitioned so as to have a predetermined area by providing a black matrix onto the anode electrode 13.
The light extracting structure 12 is formed in a specific region on the substrate 11. The light extracting structure 12 has such a structure that a film 14 made of a first translucent material and a film 15 made of a second translucent material whose refractive index differs from that of the film 14 are alternately periodically arranged as illustrated in
Subsequently, a forming method of the light extracting structure 12, a manufacturing method of the face plate 10 serving as an light-emitting substrate, and further, a manufacturing method of the image display apparatus will be described.
(1) Creation of First Translucent Material Film (
First, as illustrated in
(2) Creation of Capture Layer (
Subsequently, a capture layer 16 is formed as a film onto the film 14 of the first translucent material as illustrated in
The polymer contained in the capture layer 16 may be amorphous or crystalline. The polymer contained in the capture layer 16 is a material whose glass transition point or melting point is, desirably, lower than a glass transition point or melting point of a material constructing particles, which will be described hereinafter. For example, a thermoplastic resin which has a glass transition point and exhibits a flowability at least once by heating can be mentioned. However, if the polymer contained in the capture layer 16 is the thermoplastic resin, it is desirable that its glass transition temperature is equal to or higher than a room temperature. Even in the thermoplastic resin, it is particularly desirable to use a thermoplastic photoresist in terms of a point that the photolithography method can be used upon patterning of the capture layer 16, which will be performed in the subsequent step.
When the light extracting structure is formed by the method of the invention, it is desirable that after the capture layer 16 was formed, surface charges of the capture layer 16 are controlled for a dispersion medium 19, which will be described hereinafter. For this purpose, as a component material of the capture layer 16, it is desirable to select a high molecular material whose surface charges can be easily controlled. Specifically speaking, it is desirable to select a high molecular material having a polar functional group such as —OH, —COOH, or the like.
It is desirable to set a film thickness of capture layer 16 to a value which is equal to or less than a middle diameter (center value of particle size distribution) of the particles deposited onto the capture layer 16 in the subsequent step.
The forming method of the capture layer 16 is not particularly limited. Generally, the capture layer 16 can be formed by coating a solution of the component material of the capture layer 16 onto the film 14 of the first translucent material or the substrate 11 of the first translucent material. A coating method of the solution is not particularly limited either. For example, a well-known coating method such as spin coating method, dipping method, slit coating method, or the like can be used. Among them, the slit coating method is desirable because a thin film having a large area and a predetermined pattern can be formed.
(3) Patterning of Capture Layer (
Subsequently, the capture layer 16 formed by the just previous step is patterned so as to correspond to a pixel pattern of the image display apparatus as illustrated in
(4) Ground Process (
Subsequently, as illustrated in
In the method of the invention, desirably, the surface potential of the capture layer 16 is controlled for the dispersion medium 19 of the dispersion liquid, which will be described hereinafter, (refer to FIGS. 3E and 3E′). Much desirably, the surface potential of the capture layer 16 is raised for the dispersion medium 19. If the dispersion medium 19 is water, as a specific method of raising the surface potential of the capture layer 16, desirably, the surface treatment is executed so that a water contact angle of the surface of the capture layer 16 is equal to 30° or less. Much desirably, the surface treatment is executed so that a water contact angle of the surface of the capture layer 16 is equal to 10° or less. As a specific method of the surface treatment of the capture layer 16, a method of using an ultraviolet rays irradiation or the plasma process can be mentioned. When the component material of the capture layer 16 is a high molecular material having the polar functional group such as —OH group, —COOH group, or the like, the contact angle can be increased by further enhancing a surface polarity by the ultraviolet rays irradiation or the plasma process.
In the method of the invention, desirably, the surface potential of the particles contained in the particle dispersion liquid is controlled for the dispersion medium 19 of the dispersion liquid (refer to FIGS. 3E and 3E′). Much desirably, the surface potential of the particles 17 contained in the particle dispersion liquid (refer to FIGS. 3E and 3E′) is raised for the dispersion medium 19. Reasons why it is desirable to control the surface potential of the particles 17 as mentioned above will be described hereinafter.
(5) Applying (Coating) of Dispersion Liquid (
Subsequently, the dispersion liquid in which the particles 17 were dispersed into the dispersion medium 19 is prepared and the dispersion liquid is applied onto the capture layer 16. The particles 17 and dispersion medium 19 contained in the dispersion liquid will be described hereinbelow.
Particles
When the film 14 of the first translucent material is etched, the particles 17 dispersed in the dispersion liquid function as what is called an etching mask. A component material of the particles 17 is not particularly limited. Specifically speaking, an organic material, an inorganic material, or an organic-inorganic composite material can be used. Among those materials, silica particles are desirable. In the particles 17, it is desirable that a glass transition point or melting point of the material constructing the particles 17 is higher than the glass transition point or melting point of the material constructing the capture layer 16. As a shape of each particle 17, a state where it has a spherical shape and a high circularity and its particle size distribution is narrow is desirable from a viewpoint of raising a regularity of the concave portions which are formed in the film 14 of the first translucent material which is etching-molded and will be described hereinafter or in the substrate 11 of the first translucent material. The particle size distribution is defined by the following equation (1).
[Particle size distribution (%)]=([particle size standard deviation]/[average particle size])×100 (1)
In the equation (1), the average particle size indicates a mean value of measured diameters of 100 particles 17 extracted at random. The particle size standard deviation indicates a standard deviation obtained with respect to the 100 particles. The particle size distribution which is obtained by the equation (1) is desirably equal to 5% or less, much desirably, 2% or less.
Specifically speaking, the average particle size of the particles 17 contained in the particle dispersion liquid is obtained by selecting 100 particles among the particles 17 photographed by an electron microscope and analyzing images of the 100 particles 17.
The particle size corresponds to a pitch of the fine concave/convex pattern in the light extracting structure 12. Now, the particle size of each of the particles 17 which are used when manufacturing the image display apparatus is, desirably, equal to 3000 nm or less, much desirably, 200 to 2000 nm.
In the invention, in order to regularly capture and arrange the particles 17 onto the capture layer 16, it is desirable to control the surface potential of the particles 17 for the dispersion medium 19. As one of desirable factors to be considered when controlling the surface potential of the particles 17, there is a ζ (zeta) potential of the particles 17 dispersed in the dispersion medium 19. When considering the ζ (zeta) potential of the particles 17, as a condition adapted to regularly arrange the particles 17, it is desirable that the surface charges of the particles 17 in the dispersion medium 19 and the surface charges of the capture layer 16 are set to negative potentials. Particularly desirably, the surface charges of the particles 17 and the surface charges of the capture layer 16 are set to negative potentials and absolute values of both of those potentials are high.
The ζ (zeta) potential of the particles 17 can be measured by a commercially available ζ (zeta) potential measuring apparatus. In the case where the particles were distributed into the water, an absolute value of the average ζ (zeta) potential of the particles 17 is desirably equal to 80 mV or more. If the dispersion medium 19 is a polar dispersion medium such as water, as a method of increasing a value of the ζ (zeta) potential of the particles 17, a method whereby the number of functional groups having the polarity on the surfaces of the particles 17 is increases or a method whereby the surfaces of the particles 17 are decorated by polar molecules can be mentioned.
Dispersion Medium
The dispersion medium 19 is not particularly limited but any medium can be used so long as it is a liquid at a room temperature. For example, the water, various kinds of organic solvents, or their mixture can be used. In order to more regularly capture and arrange the particles 17 onto the capture layer 16, it is desirable that a solvent having a large surface tension is used as a dispersion medium 19. A solvent which does not dissolve or swell the capture layer 16 is desirable as a dispersion medium 19. In the invention, the water is most desirable.
Dispersion Concentration of Particles
In order to regularly capture and arrange the particles 17 onto the capture layer 16, a dispersion concentration of the particles 17 in the dispersion liquid is also important. In the invention, a concentration of the particles 17 in the dispersion liquid is desirably equal to 30 to 40 weight %.
The particle dispersion liquid is prepared in consideration of the foregoing items.
Coating of Particle Dispersion Liquid
Subsequently, as illustrated in
(6) Creation of Sediment Layer (
Subsequently, by drying the coating film and volatilizing the dispersion medium 19 from the coating film, a sediment layer 17a made of the particles 17 is formed. In this step, while the dispersion medium 19 is volatilized from the coating film, the particles 17 are put and arranged onto the capture layer 16. Although the electrostatic repulsion has occurred between the particles 17 and the capture layer 16 as mentioned above, the reason why the particles 17 are put and arranged onto the capture layer 16 in spite of the electrostatic repulsion is that a force stronger than an electrostatic repulsion force due to the electrostatic repulsion, that is, a capillary force which the dispersion medium 19 has acts. A drying method of the coating liquid in this step is not particularly limited. The substrate 11 may be naturally dried instead of the heat-drying. When the drying of the coating liquid progresses and the dispersion medium 19 is perfectly evaporated and removed, as illustrated in
(7) Capture of Particles onto Capture Layer (
Subsequently, the particles existing in the lowest layer of the sediment layer 17a are embedded into the capture layer 16 and captured. If the capture layer 16 is a layer containing the polymer, as a specific capturing method of the particles 17 existing in the lowest layer of the sediment layer 17a, a method of heating the capture layer 16 and softening the capture layer 16 can be mentioned. If the capture layer 16 is heated and softened, the particles in the lowest layer of the sediment layer 17a formed on the capture layer 16 sink into the capture layer 16 as illustrated in
(8) Removing step of Particles which are not Captured into Capture Layer (
Subsequently, among the particles 17 contained in the sediment layer 17a illustrated in
At the stage after completion of the above step, a filling rate adapted to decide a layout of the particles 17 captured in the capture layer 16 is defined by the following equation (2).
[Filling rate D(%)]=([the number of layouts of particles at each measuring position]/[the number of layouts of particles in the case where ideal hexagonal closest packing was performed])×100 (2)
An area which is measured when evaluating D is a square area in which one side is equal to a value which is 60 times as large as an area measured when the average particle size is obtained. When D is evaluated, it is desirable to measure the single-particle layer 17b at a plurality of positions and obtain its mean value and distribution σ. In the method of the invention, D is equal to 93% or more. That is, in the invention, a particle filling rate of the single-particle layer 17b is equal to 93% or more for the two-dimensional closest packing. A value obtained by subtracting σ from the mean value of D is, desirably, equal to 90% or more. The larger the value of D is, the smaller the value of σ is.
(9) Creation of Concave Portions into film or Substrate of First Translucent Material (
Subsequently, the film 14 of the first translucent material or the substrate 11 of the first translucent material is etched and a part thereof is removed, thereby forming concave portions. Thus, a concave/convex pattern of the first translucent material is formed. As a specific etching method, a general reactive ion etching method using a plasma or a general wet etching method using a solvent can be used. At this time, the particles 17 captured in the capture layer 16 function as a mask. That is, the capture layer 16 in a region other than the region where the particles 17 have been captured and the film 14 of the first translucent material or the substrate 11 of the first translucent material are etched in this step. Thus, the concave portions are formed in the film 14 of the first translucent material or the substrate 11 of the first translucent material. The region where the particles 17 have been captured remains in a convex shape. Consequently, the concave/convex pattern of the first translucent material is formed.
(10) Removal of Capture Layer (
Subsequently, the capture layer 16 remaining after the etching and the particles 17 captured in the capture layer 16 are removed from the film 14 of the first translucent material or the substrate 11 of the first translucent material. As a specific removing method, a general method using the solvent can be used. By removing the capture layer 16 and the particles 17 captured in the capture layer 16, as illustrated in
(11) Embedding by Second Translucent Material (
Subsequently, the concave portions formed in the film 14 of the first translucent material or the substrate 11 of the first translucent material mentioned above are embedded with the second translucent material. Thus, the film 15 of the second translucent material is formed. As a second translucent material, an inorganic material having a light transmittance and a predetermined refractive index in a manner similar to the first translucent material can be mentioned. However, the refractive index of the second translucent material itself differs from that of the first translucent material. As a second translucent material, a material whose refractive index is higher or lower than that of the first translucent material may be used. The film 15 of the second translucent material is formed, for example, as illustrated in
By the above steps, the light extracting structure 12 is formed onto the substrate 11.
After the light extracting structure 12 was formed, the face plate 10 (refer to
After the light extracting structure 12 was formed, as illustrated in
Subsequently, as illustrated in
The light extracting structure contained in the face plate 10 (refer to
The image display apparatus 1 described in
Example 1
The face plate is manufactured by the following method.
Step 1 (
First, the glass substrate 11 having a size of 30 mm×30 mm (high strain point low sodium glass “PD200” made by Asahi Glass Co., Ltd.) is sufficiently cleaned. Subsequently, a TiO2 film is formed onto the substrate 11 by the sputtering method, thereby forming the film 14 of the first translucent material. At this time, a thickness of film 14 of the first translucent material is set to 1.2 μm.
Step 2 (
Second, a film of the photoresist (acrylic negative type photoresist (model No. “TR2001” made by JSR Co., Ltd.)) is coated and formed onto the film 14 of the first translucent material by the slit coating method, thereby forming the capture layer 16. At this time, a film thickness of capture layer 16 is equal to 8 μm. Subsequently, a base material on which the capture layer 16 has been formed is heated and dried at 60° C. for 12 minutes. A film thickness of capture layer 16 after the drying is equal to 1.5 μm.
Step 3 (
Subsequently, a patterning of the capture layer 16 is performed by the following method. Specifically speaking, a distance between the substrate 11 and the mask is maintained at 150 μm and light of an extra-high pressure mercury lamp of 250 W made by Ushio Inc. is irradiated in the atmosphere so that an irradiation energy density in the UV420 measurement is equal to 500 mJ/cm2 by using a proximity exposing apparatus. Subsequently, an aqueous solution of 0.5% of tetramethylammonium hydroxide (hereinbelow, abbreviated to TMAM) is shower-sprayed at a room temperature and, thereafter, rinsed with the water. In this manner, the capture layer 16 is patterned and formed onto the film 14 of the first translucent material so that a film thickness is equal to 1.3 μm and a plurality of regions each having a size of 100 μm×250 μm exist.
Step 4 (
Subsequently, a surface treatment of the capture layer 16 is performed. Specifically speaking, after an excimer UV lamp was disposed at a position which is away from the high molecular layer 16 by 5 mm, light of a wavelength of 172 nm is irradiated at a rate of 1.5 J/cm2 in the atmospheric ambience.
After the light was irradiated, a water contact angle of the surface of the capture layer 16 is measured and evaluated, so that the water contact angle is equal to 10° . The capture layer 16 after the irradiation is observed and analyzed by an infrared spectrum method. Thus, it has been confirmed that the number of —OH groups was increased as compared with that in the case where the light is not irradiated. Consequently, the surface of the capture layer 16 after the light irradiation has been charged to the negative charges for the water which is used as a dispersion medium in the embodiment.
Step 5 (
Subsequently, the particles 17 and the dispersion medium 19 are mixed and the dispersion liquid is adjusted.
In the embodiment, the silica particles are used as particles 17. In the embodiment, various kinds of commercially available silica particles are previously purchased, the silica particles are dispersed into the water at a rate of 0.1 weight %, respectively, and the ζ (zeta) potentials are measured. When the ζ (zeta) potentials are measured, “Zetasizer Nono ZS” made by Sysmex Corporation is used as a measuring apparatus. When measuring, a dip cell for a low dielectric constant solvent “ZEN1002” is used as a cell for measurement. As a result of the measurement of the ζ (zeta) potentials, “Hipresica SS (N7N)” made by Ube-Nitto Kasei Co., Ltd. exhibits high negative charges of −86 mV. Therefore, in the embodiment, “Hipresica SS (N7N)” made by Ube-Nitto Kasei Co., Ltd. is used as particles 17. Grain size distribution (%) of the silica particles has a range of 2% or less. About 100 silica particles are photographed by the electron microscope. The middle diameter is obtained by analyzing the photographed images. Thus, the middle diameter of the silica particles is equal to 1.7 μmφ.
The water is used as a dispersion medium 19 of the silica particles. The silica particles and the water are mixed and a dispersion liquid is adjusted. In this manner, the particle dispersion liquids in which concentrations of the particles to the dispersion medium 19 are equal to 10, 20, 30, 40, 50, and 60 weight % are prepared.
Subsequently, the particle dispersion liquid is coated onto the high molecular layer 16 by using the spray method. At this time, a distance between the spray nozzle and the substrate 11 is set to 10 cm, a spray pressure is set to 0.2 MPa, a discharge amount is set to 0.04 ml/sec, and a coating liquid amount is set to 0.01 ml/cm2.
Step 6 (
Subsequently, the dispersion medium 19 is naturally dried at the room temperature and the sediment layer 17a made of the particles 17 is formed (
Step 7 (
Subsequently, the substrate 11 is heated and the capture layer 16 is softened. Specifically speaking, the substrate 11 is put into a baking furnace and heated. At this time, a temperature of the baking furnace is set to 230° C. When this step is executed, after the temperature of the baking furnace was set to 230° C., the substrate 11 is held at this temperature (230° C.) for 60 minutes. Then, the substrate 11 is cooled to the room temperature.
Step 8 (
Subsequently, the substrate 11 is taken out and the surface of the capture layer 16 is cleaned. Specifically speaking, the surface is cleaned by high pressure water by ejecting the micro liquid droplets from a micro jet nozzle. At this time, a pressure of the high pressure water is set to 17 MPa. After the cleaning, a cross section of the substrate is observed by the SEM. Thus, it could be confirmed that the single-particle layer 17b made of the particles 17 in which the silica particles had sunk into the capture layer 16 until a depth of 600 nm and had been captured therein was formed. By this cleaning, as illustrated in
Step 9 (
Subsequently, the single-particle layer 17b made of the particles 17 which sank into the capture layer 16 is used as a mask, the film 14 of the first translucent material is etched, a part of the film 14 of the first translucent material is removed, and the concave/convex pattern is formed. As a specific etching method, the reactive ion etching method (hereinbelow, abbreviated to RIE) is used. More specifically speaking, first, an O2 gas of 100 sccm is fed, a pressure in the apparatus is set to 2 Pa, a power of 200 W is introduced, and the RIE process is executed for 8 minutes.
Subsequently, a mixture gas of sulfur hexafluoride and argon (SF6: 160 sccm, Ar: 40 sccm) is used, a pressure in the apparatus is set to 3 Pa, and the RIE process is executed for 11 minutes at a power of 1000 W. By this process, TiO2 constructing the film 14 of the first translucent material is worked in a columnar shape. By this process, the substrate enters a state as illustrated in
Step 10 (
Subsequently, the capture layer 16 is removed by using the general peeling-off method using the solvent. As a solvent, an aqueous solution of 25% of tetramethylammonium hydroxide (TMAH) is used. Specifically speaking, the substrate 11 is dipped into the TMAH aqueous solution for 20 minutes and is ultrasonic-cleaned, thereby removing the capture layer 16.
After the capture layer 16 was removed, a cross section of the substrate is observed by the SEM. The pattern of the columnar (diameter of 1.2 μm; a height of 1.2 μm) film 14 of the first translucent material is formed in correspondence to the arrangement position of the particle 17. An average pitch of the columns of the film 14 of the first translucent material is equal to 1.7 μm that is the same as the diameter of the particle 17.
Step 11 (
Subsequently, a circumference of the columnar pattern of the film 14 of the first translucent material formed by the previous step is embedded with a material whose refractive index is smaller than that of the film 14 of the first translucent material, thereby forming the film 15 of the second translucent material. Specifically speaking, first, a dibutylether solution (coating type insulating film material, “Aquamica NN120-20” made by AZ Electronic Materials Co., Ltd.) of polysilazane is coated onto the substrate 11 by the spray method. Subsequently, the substrate 11 on which the polysilazane film has been formed is baked at 450° C. for 30 minutes by using an infrared furnace. A cross section of the substrate after the baking is observed by the SEM. As illustrated in
Step 12 (
Subsequently, an ITO film is formed onto the film 15 of the second translucent material by the sputtering method, thereby forming the anode electrode 13.
Step 13 (
Subsequently, an IPA solution in which ethyl cellulose, phosphor particles, and isopropyl alcohol (IPA) have been mixed is adjusted. Then, the adjusted IPA solution is dripped as droplets onto the anode electrode 13 and spin-coated and, thereafter, dried, thereby forming an ethyl cellulose film (phosphor film 18) containing the phosphor particles. With respect to the formed phosphor film 18, a luminance of the phosphor at the time of the UV (wavelength: 254 nm) irradiation is evaluated.
Every 50 positions in the region where the light extracting structure has been formed and the region where the light extracting structure is not formed are sampled and the luminance at each position is measured by using the luminance evaluating apparatus of
From the results of Table 1, it has been confirmed that when the mean value of the filling rate of the particles 17 which are filled onto the capture layer 16 is equal to 93% or more, there is no luminance deviation and the large light extracting efficiency can be accomplished. That is, by setting the filling rate of the particles 17 which are filled onto the capture layer 16 to 93% or more for the two-dimensional closest packing, the manufacturing method of the image display apparatus in which the luminance has been improved can be provided.
In Example 1, when step 4 is executed, the surface treatment of the capture layer 16 is executed so that a water contact angle of the surface of the capture layer 16 is equal to 70°. Specifically speaking, an intensity of the UV light which is irradiated to the capture layer 16 is set to 1.5 J/cm2. When step 5 is executed, the particles whose ζ (zeta) potential is equal to −70 mV (“SHINSHIKYU™ Series SW” made by JGC Catalysts and Chemicals Ltd.) are used as particles 17. The face plate is manufactured by a method similar to that in Example 1 except for the above conditions.
In this Comparative Example, after step 4, when the capture layer 16 is analyzed by the infrared spectrum method, an increase in number of —OH groups is observed as compared with that before the UV light is irradiated. However, an increase amount of the —OH groups is smaller than that in Example 1. Therefore, in this Comparative Example, although the surface of the capture layer 16 after the UV light was irradiated has a negative polarity for the water serving as a dispersion medium 19, an absolute value of the charge is smaller than that of Example 1.
With respect to the substrate 11 after step 8 was executed, the filling rate of the particles is evaluated in a manner similar to Example 1. Further, with respect to the substrate 11 after step 13 was executed, the light extracting efficiency and the luminance deviation are evaluated in a manner similar to Example 1. Evaluation results are shown in Table 2. In this Comparative Example, a shape of the film of the first translucent material formed on the substrate is a columnar shape having a diameter and a height similar to those in Example 1 and has an average pitch similar to that in Example 1.
From the results of Table 2, in this Comparative Example, the mean value of the filling rate of the particles is equal to 85% or less in all of the conditions. When comparing with the results of Example 1, in the case of the face plate manufactured in this Comparative Example, the light extracting efficiency and the luminance deviation are inferior to those in Example 1.
From the results of Example 1 and Comparative Example 1, in order to accomplish the face plate in which there is no luminance deviation and the light extracting efficiency is large, it is necessary to set the mean value of the filling rate of the particles to 93% or more. In order to set the mean value of the filling rate of the particles to 93% or more, it is necessary to control the surface charges of the high molecular layer 16. The present inventors et al. consider that, as factors of it, if the surface charges of the high molecular layer 16 are small, when the particle dispersion liquid is coated and dried, the particles 17 are liable to be adsorbed to the substrate, and this becomes a factor of obstructing the particle layout.
In Comparative Example 2, when step 5 is executed, particles whose surfaces have been decorated by a surface decorating material are used. Specifically speaking, as a surface decorating material of the particles 17, a polydiallyl dimethylammonium chloride is added to the dispersion medium by 0.001 weight % and sufficiently stirred. The face plate is manufactured by a method similar to that in Comparative Example 1 except for the above conditions. The ζ (zeta) potential at the time when the particles were dispersed to the water (dispersion medium) by 0.1 weight % by the surface decoration is equal to +35 mV. Other conditions are set to be identical to those in Comparative Example 1.
With respect to the substrate 11 after step 8 was executed, the filling rate of the particles is evaluated in a manner similar to Example 1. Further, with respect to the substrate 11 after step 13 was executed, the light extracting efficiency and the luminance deviation are evaluated in a manner similar to Example 1. Evaluation results are shown in Table 3. In this Comparative Example, a shape of the film of the first translucent material formed on the substrate is a columnar shape having a diameter and a height similar to those in Example 1 and has an average pitch similar to that in Example 1.
From the results of Table 3, in this Comparative Example, the mean value of the filling rate of the particles is equal to 65% or less in all of the conditions. When comparing with the results of Example 1, in the case of the face plate manufactured in this Comparative Example, the light extracting efficiency and the luminance deviation are inferior to those in Example 1.
From the results of Example 1 and Comparative Example 2, in order to accomplish the face plate in which there is no luminance deviation and the light extracting efficiency is large, it is necessary to set the mean value of the filling rate of the particles to 93% or more. In order to set the mean value of the filling rate of the particles to 93% or more, it is necessary to control the surface charges of the high molecular layer 16 to a negative polarity. The present inventors et al. consider that, as factors of it, if the surface charges of the high molecular layer 16 and the surface charges of the particles 17 have opposite polarities, when the particle dispersion liquid is coated and dried, the particles 17 are more liable to be adsorbed to the substrate, and this becomes a factor of obstructing the particle layout.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2010-205720,filed Sep. 14, 2010,which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-205720 | Sep 2010 | JP | national |
