JP2010102972A - Flat panel display, display apparatus using it, and phosphor film forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high luminance and high efficiency of a display by attaining high density of a fluorescent film in a flat panel display. <P>SOLUTION: By coating the phosphor powder surface with a surfactant, the phosphor surface friction is reduced and adhesion force between particles is reduced, and thereby, fluorescent film density is improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flat panel display used in a flat television such as a plasma display panel (hereinafter also referred to as PDP) and a display device using the flat panel display, and relates to improvement of a fluorescent film for realizing high efficiency.

  Plasma display panels are used in large-screen, thin, and flat-screen televisions, and their performance is increasing. Further improvement in efficiency is desired. In addition, miniaturization of cell size is also progressing due to high definition.

  FIG. 2 is an exploded perspective view showing a part of the structure of an example of a typical plasma display panel. The plasma display panel has a structure in which a front substrate and a rear substrate are bonded together, and a discharge gas is sealed between the substrates.

  The front substrate has a plurality of electrode pairs each composed of a transparent electrode 2 and a bus electrode 3 (usually one of the electrode pairs is called an X electrode) for sustain discharge (also called display discharge) on the front plate glass 1. The other is referred to as a Y electrode (only one pair is shown in FIG. 2), and these electrode pairs are covered with a dielectric 4 and a protective film 5. The back substrate has address electrodes 9 on a back plate glass 6, and the address electrodes 9 are covered with a dielectric 8. Further, partition walls 7 are formed on the dielectric 8, and red, blue and green phosphor films 10 are formed between the partition walls 7.

The front substrate and the back substrate are aligned so that the electrodes on the front substrate side and the electrodes on the back substrate side are substantially orthogonal to each other (in some cases, simply crossing each other). Sealing is performed, and a discharge gas is sealed in a gap between the two substrates, and a plurality of cells are formed between the two substrates. By selectively applying a voltage to the sustain electrode pair on the front substrate side and the address electrode on the rear substrate side, a discharge is generated in a desired cell among the plurality of cells. Vacuum ultraviolet rays are generated by the main discharge, and the generated vacuum ultraviolet rays excite each color phosphor film 10 to emit red, blue, and green light, thereby performing full color display. The back substrate may have the structure of FIG.
In addition, an optical filter 11 is installed on the forefront of the panel to form a product set.

  FIG. 4 shows an example of a cross-sectional view of the plasma display panel. As a method for improving the luminous efficiency of the plasma display, a method of increasing the phosphor film thickness can be considered. However, as the phosphor film thickness is increased, the discharge space is reduced, so that the discharge efficiency is lowered, and the efficiency of the entire cell is lowered.

  If the film density of the phosphor film can be improved, the amount of phosphor used is constant, the film thickness can be reduced, the discharge efficiency can be improved by increasing the discharge space, and the plasma display can be made more efficient. it can.

  Phosphor particles used for plasma displays are becoming smaller particles, and a particle size of 0.05 to 0.3 μm is proposed for the current particle size of 2 to 5 μm (for example, patents). Reference 1).

The inter-particle space volume ratio in the powder layer which is a laminate of particles is called a void ratio. This space ratio also changes depending on the particle shape and particle size distribution, but also changes depending on the particle diameter due to the relationship between the weight of the powder particles and the interparticle adhesion force.
The roller seeks the relationship between the particle diameter and the space ratio. When the particle diameter is less than the limit particle diameter of about 10 μm or less, the space ratio increases rapidly as the particle diameter decreases due to the interparticle adhesion force. (Non-Patent Document 1).

  The particle size of the phosphor for plasma display is below the critical particle size, and the filling rate in the powder layer is affected by the adhesion between particles. Therefore, the density of the fluorescent powder film can be improved by reducing the adhesion between particles.

  The ac type PDP having a so-called three-electrode / surface discharge structure has been described above, but it goes without saying that this patent is applicable to all PDPs. For example, the present invention can be applied to a dc type PDP (for example, see Non-Patent Document 2) and a counter discharge type PDP (for example, see Non-Patent Document 3).

In the PDP having the above-described structure, “ultraviolet rays are generated by the main discharge, and the generated vacuum ultraviolet rays excite each color phosphor to emit red, blue, and green, and perform full color display”. It goes without saying that the present invention can be applied not only to the case where the phosphor is excited with vacuum ultraviolet rays but also to the case where the phosphors are excited with normal ultraviolet rays. Further, in the PDP having the above structure, visible light of red, blue, and green is generated by the phosphor. However, the present invention can be applied not only to such a structure but also to a structure that directly generates visible light by discharge. Needless to say. Furthermore, the visible light is not limited to red, blue, and green light, and it goes without saying that the present invention can be applied to the case of generating visible light of other colors, and further to generating monochromatic visible light. In addition to the PDP, the present invention can be applied to all flat panel displays such as an FED (Field Emission Display) in which the excitation source of the phosphor is an electron beam.

JP 2002-88355 A Particle / Powder Optics (Nikkan Kogyo Shimbun, 2002) 40 “Latest Plasma Display Technology” (ED Research, 1996) P.121 SID 93 digest P.I. 173

  The problem to be solved by the present invention is to improve the light emission efficiency in the flat panel display, and to improve the light emission intensity by realizing the improvement of the film density of the fluorescent film.

The outline of typical inventions among inventions disclosed in this document will be described as follows.
(1) A flat panel display having a fluorescent film formed using a phosphor having a surfactant attached to the surface. (2) A flat panel having a fluorescent film formed using a phosphor having a higher alcohol attached to the surface. Display (3) A flat panel display having a fluorescent film formed using a phosphor with higher fatty acid attached to the surface. (4) A fluorescent film formed using a phosphor with a nonionic dispersant attached to the surface. Flat panel display (5) Flat panel display (6) having a fluorescent film formed using a phosphor with a polymeric dispersant adhering to the surface (6) The fluorescent film density is 2.0 g / cm ³ or more (7) Display device using the flat panel display described in (1) to (6) above (8) Phosphor powder surface A method for forming a phosphor film, comprising: a step of attaching a surfactant to the substrate; and a phosphor forming step in which the phosphor film density after the film forming step is 2.0 g / cm 3 or more.

  According to the present invention, a high-density fluorescent film can be realized, and a high-efficiency flat panel display and a display device using the same can be realized.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. In all the drawings for explaining the present invention, the same reference numerals are given to those having the same function, and the description thereof will not be repeated.

  FIG. 5 shows a typical cross-sectional view of a PDP. FIG. 6 shows the state of the phosphor particles in the phosphor film. In the current phosphor particles, the interparticle adhesion force on the phosphor particle surface is large, so the porosity in the phosphor film is large and the film density is low.

  On the other hand, the present invention is characterized in that a part or the whole of the surface of the phosphor particles 12 is coated with the surfactant 13 as shown in FIG. 7 or FIG. As shown in FIG. 9, since the adhesion between particles on the phosphor surface is reduced by the coating of the surfactant, the filling rate of the particles is improved, and the density of the fluorescent film can be improved and the film thickness can be reduced. Accordingly, the discharge space can be widened as shown in FIG. 10, and the discharge efficiency can be improved. FIG. 10 shows an example of the present invention. The fluorescent film is not limited to one composed of one phosphor layer. It is desirable that the surfactant is thermally decomposed during or after the film forming process so that the amount of residue on the phosphor particle surface is small.

Surfactants used in the present invention include higher alcohols such as octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, 2 octyldodecanol, cabrylic acid, cabric acid, laurin In addition to higher fatty acids such as acid, myristic acid, palmitic acid, stearic acid, and nonionic dispersants such as alkylphenyl ether, alkylamine, sorbitan fatty acid ester,
Polymeric dispersants such as polyacrylates, polycarboxylates, and polyoxyalkylenes can also be used.

The above surfactants are used by dissolving in an organic solvent such as hexane, ethyl alcohol, methyl alcohol, chloroform, ether or the like as necessary. Also,
These surfactants can be used alone or as a mixture.

The present invention can be applied to many phosphors. For example, as a red phosphor, (Y, Gd) BO ₃ : Eu, Y ₂ O ₃ : Eu, (Y, Gd) ₂ O ₃ : Eu, Y ₂ O ₂ S: Eu, YVO ₄ : Eu, Y (P, V) O ₄ : Eu, (Y, Gd) (P, V) O ₄ : Eu, and the like, as a green phosphor, Zn ₂ SiO ₄ : Mn, YBO ₃ : Tb, (Y, Gd) BO ₃ : Tb, ZnS: Cu, Al, Y ₂ SiO ₅ : Tb, etc., and blue phosphors include BaMgAl ₁₀ O ₁₇ : Eu and CaMgSi ₂ O ₆ : Eu, Sr ₃ MgSi ₂ O ₈ : Eu, (Ca, Sr) ₃ MgSi ₂ O ₈ : Eu, ZnS: Ag, ZnS: Ag, Al, various oxides such as Al, sulfide phosphors, etc. can be used. Yes, multiple phosphors can be mixed Noh. Further, although it can be applied to all three-color phosphors, it may be applied only to phosphors of a necessary color.

The surface of these phosphor particles is coated with the surfactant. As a coating method, the phosphor particles and the surfactant are stirred in the same container by using a defoaming stirrer, a ball mill, a three roll, an automatic mortar, a raking machine, etc., and the phosphor particles in the surfactant solution. The method of stirring and drying in the inside can be used. Further, the same effect can be obtained by mixing a surfactant and a phosphor in the vehicle at the time of preparing the phosphor paste used at the time of film formation.

  A comparative example is described below.

Commonly used phosphors for PDP include (Y, Gd) BO ₃ : Eu (red phosphor), Zn ₂ SiO ₄ : Mn (green phosphor), BaMgAl ₁₀ O ₁₇ : Eu (blue) The tapping density of the phosphor powder was measured using a phosphor.

After putting a certain weight of phosphor powder into a cylindrical container, drop the container 200 times from a height of 20 cm to fill the phosphor powder, and calculate the ratio between the input weight and the volume indicated by the phosphor powder. The bulk density was determined. As shown in Table 1, the bulk densities of the red, green, and blue phosphors were 1.16, 1.03, and 0.83 (g / cc), respectively.
Next, using these phosphors, the PDP shown in FIG. 2 was produced.

  At this time, red, blue, and green phosphor films 10 were formed between the barrier ribs 7 in the following procedure. In other words, 40 parts by weight of the phosphor and 60 parts by weight of the vehicle are mixed to form a phosphor paste, which is applied by screen printing, volatile components in the paste are removed, and organic substances are burned and removed by a drying and firing process. Formed.

  When the thickness of the fluorescent film of each color in the manufactured PDP was measured and the fluorescent film density was calculated, the fluorescent film density of each color was 1.7, 1.4, 1.3 (see Table 2). g / cc).

A plasma display panel in which a discharge gas was sealed by bonding the back substrate on which the phosphor layer was formed to the front substrate was manufactured, and the luminance was evaluated by connecting a drive circuit. As a result, the luminance was 500 cd / m ² . This value is hereinafter referred to as the luminance standard (100).

  The same red, green, and blue phosphors as in Comparative Example 1 were used, but in this example, the phosphor was coated with a surfactant, which was different from the comparative example. The phosphor surface was modified using sorbitan fatty acid ester as a surfactant.

The phosphor powder and sorbitan fatty acid ester were stirred with a defoaming stirrer at 2000 rpm for 4 minutes to prepare a phosphor powder whose surface was coated with a surfactant. At this time, products having different surfactant addition concentrations were prepared, and the bulk density was measured. As an example, the results with a green phosphor (Zn ₂ SiO ₄ : Mn) are shown in FIG. The bulk density was improved by the addition of the surfactant, and the bulk density was improved by the phosphor surface coating. Similar effects were shown for red and blue phosphors. As an example, characteristic results when using red, green, and blue phosphors surface-modified with a surfactant addition concentration of 0.1 g / cc are shown below. As shown in Table 1, the bulk density of the surface-modified phosphor was improved in all three colors with respect to the comparative example. In addition, the fluorescent film thickness of the PDP produced using this phosphor is reduced for all three colors compared to the comparative example, and as shown in Table 2, the density of each color fluorescent film is 2 g / cc or more. Compared with the comparative example, a high-density fluorescent film was realized. The light emission luminance of the PDP was improved to 110 compared to the comparative example (100). Brightness can be improved by improving the luminous efficiency of the fluorescent film by increasing the density of the fluorescent film and by improving the discharge efficiency by expanding the discharge space.

A sample was prepared and evaluated in the same manner as in Example 1 except that a polyoxyalkylene derivative was used as the surfactant. As an example, FIG. 12 shows the surfactant addition concentration-bulk density change when the surface of a green phosphor (Zn ₂ SiO ₄ : Mn) is coated.

  The bulk density was improved by the addition of the surfactant, and the bulk density was improved by the phosphor surface coating. Similar effects were shown for red and blue phosphors. As an example, characteristic results when using red, green, and blue phosphors surface-modified with a surfactant addition concentration of 0.1 g / cc are shown below. As shown in Table 1, the bulk density of the surface-modified phosphor was improved in all three colors with respect to the comparative example. In addition, the phosphor film thickness of the PDP produced using this phosphor is reduced for all three colors compared to the comparative example, and as shown in Table 2, the density of each phosphor film is 2 g / cc or more. For example, a high-density fluorescent film was realized. The light emission luminance of the PDP was improved to 107 with respect to the comparative example (100). Brightness can be improved by improving the luminous efficiency of the fluorescent film by increasing the density of the fluorescent film and by improving the discharge efficiency by expanding the discharge space.

A sample was prepared and evaluated in the same manner as in Example 1 except that polycarboxylate (20% solution in toluene) was used as the surfactant. As an example, FIG. 13 shows the surfactant addition concentration-bulk density change when the surface of a green phosphor (Zn ₂ SiO ₄ : Mn) is coated.

  The bulk density was improved by the addition of the surfactant, and the bulk density was improved by the phosphor surface coating. Similar effects were shown for red and blue phosphors. As an example, the characteristic results when using a red, green and blue phosphor surface-modified with a surfactant addition concentration of 0.1 g / cc are shown below. As shown in Table 1, the bulk density of the surface-modified phosphor was improved in all three colors with respect to the comparative example. In addition, the fluorescent film thickness in the PDP produced using this phosphor is reduced in all three colors compared to the comparative example, and as shown in Table 2, the density of the fluorescent film of each color is 2 g / cc or more. A high-density fluorescent film was realized. The light emission luminance of the PDP was improved to 105 with respect to the comparative example (100). Brightness can be improved by improving the luminous efficiency of the fluorescent film by increasing the density of the fluorescent film and by improving the discharge efficiency by expanding the discharge space.

  A sample was prepared and evaluated in the same manner as in Example 1 except that cetyl alcohol (20% solution in hexane) was used as the surfactant.

  As an example, the characteristic results when using a red, green and blue phosphor surface-modified with a surfactant addition concentration of 0.1 g / cc are shown below. As shown in Table 1, the bulk density of the surface-modified phosphor was improved in all three colors with respect to the comparative example. In addition, the phosphor film thickness of the PDP produced using this phosphor is reduced for all three colors compared to the comparative example, and as shown in Table 2, the density of each phosphor film is 2 g / cc or more. For example, a high-density fluorescent film was realized. The light emission luminance of the PDP was improved to 105 with respect to the comparative example (100). Brightness can be improved by improving the luminous efficiency of the fluorescent film by increasing the density of the fluorescent film and by improving the discharge efficiency by expanding the discharge space.

  A sample was prepared and evaluated in the same manner as in Example 1 except that stearic acid (20% solution in chloroform) was used as the surfactant.

  As an example, the characteristic results when using a red, green and blue phosphor surface-modified with a surfactant addition concentration of 0.1 g / cc are shown below. As shown in Table 1, the bulk density of the surface-modified phosphor was improved in all three colors with respect to the comparative example. In addition, the phosphor film thickness of the PDP produced using this phosphor is reduced for all three colors compared to the comparative example, and as shown in Table 2, the density of each phosphor film is 2 g / cc or more. For example, a high-density fluorescent film was realized. The light emission luminance of the PDP was improved to 107 with respect to the comparative example (100). Brightness can be improved by improving the luminous efficiency of the fluorescent film by increasing the density of the fluorescent film and by improving the discharge efficiency by expanding the discharge space.

The figure which shows the outline of the flat panel display of this invention. The perspective view which shows the structure of a plasma display panel. It is a perspective view which shows an example of the back substrate of a plasma display. Sectional drawing of a plasma display panel. Sectional drawing of a plasma display panel. The figure explaining the mode of the fluorescent substance particle in a fluorescent film. The figure which shows the surface-coated fluorescent substance particle in an example of this invention. The figure which shows the surface-coated fluorescent substance particle in an example of this invention. The figure which shows the mode of the fluorescent substance particle in the fluorescent film in an example of this invention. The figure explaining the film thickness of a fluorescent film. The figure explaining surfactant addition concentration-bulk density change. The figure explaining surfactant addition concentration-bulk density change. The figure explaining surfactant addition concentration-bulk density change.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Front plate glass, 2 ... Transparent electrode, 3 ... Bus electrode, 4 ... Dielectric,
5 ... Protective film, 6 ... Back plate glass, 7 ... Partition, 8 ... Dielectric,
9 ... Address electrode, 10 ... Fluorescent film, 11 ... Optical filter,
12 ... phosphor particles, 13 ... surfactant.

Claims (8)

  Flat panel display having a phosphor film formed using a phosphor with a surfactant attached to the surface   The flat panel display according to claim 1, wherein the surfactant is a higher alcohol.   The flat panel display according to claim 1, wherein the surfactant is a higher fatty acid.   The flat panel display according to claim 1, wherein the surfactant is a nonionic dispersant.   2. The flat panel display according to claim 1, wherein the surfactant is a polymer dispersant.   The flat panel display according to claim 1, wherein the density of the fluorescent film is 2.0 g / cm3 or more.   A display device using the flat panel display according to claim 1.   A method for forming a phosphor film, comprising: a step of attaching a surfactant to the surface of the phosphor powder; and a phosphor forming step in which the density of the phosphor film after the film forming step is 2.0 g / cm 3 or more.

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