JP5241070B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device using light emitted from a phosphor.

  The image display device in the present invention is a device that displays image information by exciting a phosphor by electron beam irradiation or light irradiation to emit light. This refers to a cathode ray tube (particularly a projection type cathode ray tube), a low-speed electron beam display panel (such as a field emission display (FED)), a plasma display panel (PDP) and the like. In addition, the image display apparatus includes the entire system in which the cathode ray tube or the panel is used as a display unit and a driving device or an image processing circuit is incorporated to display an image. Further, in addition to the self-luminous image display device as described above, a non-self-luminous image display device including a light source as a backlight or a sidelight in a non-luminous display unit such as a liquid crystal is also included.

  Hereinafter, among the image display devices, a field emission display (FED) will be mainly described. In a field emission display (FED), which is a thin image display device that displays a color image, an image is displayed by exciting a fluorescent film with an electron beam accelerated at a voltage of 15 kV or less. In the phosphor film for low-energy electron beam excitation used in such a display, the electric resistance is reduced so that the phenomenon that the electrons are accumulated on the surface and the penetration of the electrons into the phosphor due to the repulsion of the electrons is prevented (charge up). Low is required. Currently, a film using a sulfide-based phosphor such as ZnS: Ag is known as a fluorescent film satisfying such conditions. However, these sulfide-based phosphors are easily decomposed by damage caused by electron beam irradiation, and by releasing a gas containing S element, the luminance of the phosphor is lowered and the cathode of the electron source is deteriorated. These shorten the life of the display.

Also, phosphors such as ZnGa ₂ O ₄ : Mn, Y ₃ (Al, Ga) ₅ O ₁₂ : Tb, CaMgSi ₂ O ₆ : Eu that are difficult to decompose and have little luminance degradation have high electrical resistance, It is easy to charge up and high brightness is difficult to obtain.

For this reason, as disclosed in Japanese Patent Application Laid-Open No. 08-171868 (Patent Document 1), a method in which a conductive material such as In ₂ O ₃ , SnO ₂ , ZnO or the like is mixed and contained has been proposed. However, since these conductive materials are non-luminous substances, the amount of the phosphor in the film is reduced when an amount (for example, 20% or more) sufficient to impart sufficient conductivity to the phosphor is mixed. The brightness cannot be improved to a sufficient level.

Japanese Unexamined Patent Publication No. 08-171868

  In the prior art, it has been difficult to solve both the problems of improving the deterioration of the phosphor and improving the luminance. Accordingly, an object of the present invention is to provide an image display device with little deterioration and high luminance.

  An object of the present invention is to provide an image display apparatus having a phosphor film in which phosphor particles are laminated, injecting energy into the phosphor film from one direction to excite the phosphor to emit light, and performing display using the light. The phosphor film is composed of at least two kinds of phosphors, and the weight of the first phosphor in the whole phosphor film includes the first and second and subsequent phosphors, and the weight ratio to the total phosphor weight is x. If the range of x is 0 <x ≦ 0.9 and the weight ratio of the first phosphor to the total weight of the outermost surface layer of the phosphor layer on the energy input side is y, the range of y is (x It is achieved by an image display device characterized by having a fluorescent film satisfying +0.1) ≦ y ≦ 1.

  That is, the layer on the side irradiated with the electron beam reduces the deterioration by increasing the first phosphor that is less deteriorated, and the entire phosphor film is formed by the second and subsequent phosphors that exhibit high luminance in the low-speed electron beam. By increasing the luminance, an image display device having a long lifetime and high luminance is provided.

  According to the present invention, it is possible to obtain a fluorescent film and an image display device having high luminance and a long lifetime.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of an example of the phosphor film of the present invention. A transparent electrode 2 is provided on the face panel 1 as a display surface, and a fluorescent film is further formed thereon. The phosphor film is composed of 3 as the second and subsequent phosphors and 4 as the first phosphor.

  In the example of FIG. 1, the entire film is formed of phosphor particles that are stacked in three layers. Here, the first phosphor layer, the second phosphor layer, and the third phosphor layer are referred to from the upper layer. The thicknesses of the fluorescent film and the phosphor layer in this figure are examples, and other film thicknesses are possible. In the example of FIG. 1, the transparent electrode is provided on the face panel. Instead, an aluminum layer may be provided on the phosphor layer to form an electrode.

  Here, if a phosphor showing good luminance in a low-speed electron beam is used as the second phosphor, a high-luminance phosphor film can be obtained. Moreover, a long-life phosphor film can be obtained by using a phosphor that is resistant to deterioration and is not easily decomposed by electron beam irradiation as the first phosphor.

  The reason why the configuration of the present invention is effective will be described below. An electron beam that excites the phosphor to emit light is irradiated from the opposite side of the face panel. The irradiated electron beam passes through the phosphor layer in the phosphor film, and the intensity is attenuated. For this reason, the excitation electron beam intensity is strong in the uppermost first phosphor layer in FIG. 1 on the electron beam irradiation side, and the excitation electron beam intensity is weak in the second to third phosphor layers below the face panel side, This results in uneven strength in the thickness direction of the film. This is because, in the second to third phosphor layers, the excitation is weak, so that it is difficult to obtain a high luminance of the phosphor. In the first phosphor layer, the excitation is strong and the deterioration is severe, and the influence of decomposition of the phosphor is likely to appear. It is shown that. Here, if the configuration of the present invention is used, it is possible to compensate for the low luminance in the second to third phosphor layers and suppress the deterioration in the first phosphor layer, resulting in high luminance and little deterioration. A fluorescent film can be obtained. In addition, if a phosphor with little saturation of luminance by strong excitation is used for the first phosphor layer, a phosphor film with higher luminance can be obtained.

One of the methods for realizing the above configuration uses a phosphor with little deterioration as the first phosphor. That is, as an example of measurement conditions, the luminance after irradiating an electron beam of 10 μA / cm ² for 2000 hours, The ratio of the initial luminance is larger than that of the second and subsequent phosphors.

Furthermore, the first use of the phosphor saturation with less brightness as a phosphor, i.e., in the electron beam excitation of ^{10μA / cm 2 ~20μA / cm 2} , the rate of increase in emission luminance, the increase from the first phosphor If a material larger than the above is used, a fluorescent film with higher luminance can be obtained.

Examples of the phosphor include ZnS: Ag, Al, ZnS: Cu, Al, Y ₂ O ₂ S: Eu, ZnO: Zn, Zn ₂ SiO ₄ : Mn, etc. as the second phosphor. ZnGa ₂ O ₄ , ZnGa ₂ O ₄ : Mn, Y ₂ SiO ₅ : Tb, Y ₃ (Al, Ga) ₅ O ₁₂ : Tb, Y (P, V) O ₄ : Eu, Y ₂ O ₃ : Eu, CaMgSi ₂ O ₆ : Eu and the like. Furthermore, in producing the present invention, various combinations other than the phosphors listed here can be considered.

  Further, by using a phosphor containing S element as the second phosphor, the amount of gas containing S element can be reduced, and deterioration of the electron source cathode can be reduced.

Furthermore, in order to obtain better characteristics by utilizing the configuration of the present invention, the ratio that the area occupied by the first phosphor occupies the area of the entire surface is a, the specific gravity of the first phosphor is u, The range of a is the weight ratio of the first phosphor to the weight of the phosphor in the entire phosphor film when the average specific gravity of the whole phosphor including the first and second and subsequent phosphors is v. In the image display device having a phosphor film with {(x + 0.1) v / u} ^2/3 ≦ a ≦ 1 with respect to the described weight ratio x, strong electron beam irradiation to the first phosphor is ensured Therefore, higher luminance can be obtained.

  Further, by making the average particle size of the first phosphor smaller than the average particle size of the second phosphor, the effect of covering the second phosphor is enhanced, and a phosphor film with less deterioration is obtained. Can do. Here, an average particle diameter means the value shown in the center of a particle size distribution among the results of measuring the particle size distribution of fluorescent substance powder with a Coulter meter.

  In addition, in the configuration of the present invention, it is more desirable if the electrical resistivity of each phosphor layer is a different value. This is because the amount of current flowing through each layer during excitation is different and the path through which the current flows is different, so that each layer has an optimum electrical resistivity to reduce the charge-up of electrons. Here, as the electrical resistivity, a value measured by a four-terminal method using electrodes deposited on the surface of a single film of each phosphor is used.

It is necessary to select an optimum electrical resistivity relationship between the first phosphor and the second and subsequent phosphors depending on the film structure, the phosphor material, the electron beam acceleration voltage, and the like. In general, a phosphor film composed only of phosphors with high electrical resistivity does not have good characteristics. When phosphors with high electrical resistivity are used, it is often the case that desirable characteristics are obtained when combined with phosphors with low electrical resistivity.
These differences in electrical resistivity can be realized by differences in phosphor materials as one method. Examples include phosphors with high electrical resistivity such as ZnGa ₂ O ₄ : Mn, Y ₂ SiO ₅ : Tb, and phosphors with low electrical resistivity such as ZnS: Ag, Al, ZnO: Zn, etc. It is done.

Y ₃ (Al, Ga) ₅ O _12-a : Tb phosphor (where a is a number greater than or equal to 0) has a different electrical resistivity depending on the concentration of O atoms, and Y ₃ (Al, The Ga) ₅ O _12-a : Tb phosphor can be made lower in electrical resistivity than the Y ₃ (Al, Ga) ₅ O ₁₂ : Tb phosphor with a = 0. A configuration in which the former phosphor is used as the first phosphor and the latter phosphor is used as the second phosphor is also considered as one aspect of the present invention. This difference in electrical resistivity depending on the oxygen concentration applies to many phosphors mainly composed of oxides, and the same configuration is possible in other phosphors mainly composed of oxides.

Furthermore, in order to realize the difference in resistivity between the layers, there is a method of containing a conductive substance such as In ₂ O ₃ or SnO ₂ . This can be realized by including a conductive substance in one of the phosphors. Moreover, it can implement | achieve by making both said fluorescent substance contain an electroconductive substance, and making content of the electroconductive substance of each fluorescent substance into a different quantity. If these configurations of the present invention are used, the conductive material can be reduced as compared with the case where the conductive material is uniformly contained in the entire fluorescent film, and a high-luminance fluorescent film can be obtained.

  The effect of the present invention is not limited to the type of excitation source, but is effective in all types of excitation sources that excite phosphors such as various electron beam sources and ultraviolet light sources.

  Examples of the present invention will be specifically described below.

A phosphor film having the structure shown in FIG. 1 was prepared by a method in which a phosphor slurry was used and applied to two layers while changing the phosphor mixing ratio. Using this phosphor film for the display surface, a field emission display panel having the structure shown in FIG. 2 was produced. A ZnS: Cu, Al phosphor was used as the second phosphor, and a Y ₃ (Al, Ga) ₅ O ₁₂ : Tb phosphor was used as the first phosphor. Here, when the weight ratio of the first phosphor in the entire phosphor film to the total phosphor weight including the first and second and subsequent phosphors is x, x is changed from 0.1 to 0.9, The range of y was changed to (x + 0.1) ≦ y ≦ 1, where y represents the weight ratio of the first phosphor to the total weight of the outermost surface layer of the phosphor film on the energy input side.

As a comparison with the prior art, the entire film is made of a ZnS: Cu, Al phosphor, and the whole film is made of a Y ₃ (Al, Ga) ₅ O ₁₂ : Tb phosphor. Films were also prepared, and a field emission display panel using these fluorescent films on the display surface was prepared. The average particle diameter of each phosphor was 5 μm to 6 μm.

In these panels, an electron beam of 10 μA / cm ² was irradiated, and the brightness of each fluorescent film was compared. Further, the brightness after irradiation with an electron beam of 10 μA / cm ² for 2000 hours was measured, and the degree of deterioration was measured. All luminances were measured with a Si phototransistor 20 cm away from the film surface.

Table 1 shows the measurement results. As an example, the measurement data of the phosphor film of the present invention is shown for x = 0.3 and y = 0.9. As Comparative Example 1, measurement data of a phosphor film of ZnS: Cu, Al phosphor is shown. As Comparative Example 2, measurement data of a phosphor film of Y ₃ (Al, Ga) ₅ O ₁₂ : Tb phosphor is shown. The luminance is shown as relative luminance with Comparative Example 1 as 100. The brightness of the example is higher than the brightness of Comparative Examples 1 and 2. In addition, the luminance after deterioration is standardized with the initial luminance before deterioration as 100. It can be seen that the post-deterioration luminance of the example exceeds the post-deterioration luminance of Comparative Examples 1 and 2, and the deterioration is small. From these, it was shown that both the luminance and deterioration characteristics of the phosphor film of the present invention are superior to those of the prior art phosphor films.

  As described above, by using the present invention, it is possible to provide a fluorescent film and an image display device having high luminance and a long lifetime.

  In addition, although an example using an electron beam source called Spindt type was shown here, all types such as a metal-insulator-metal (MIM) type electron beam source and an electron beam source using carbon nanotubes (CNT) are shown. The present invention is also effective in an electron beam source.

A fluorescent film having the structure shown in FIG. 1 was prepared by a method of applying two layers using a phosphor slurry. Using this phosphor film for the display surface, a field emission display panel having the structure shown in FIG. 2 was produced. A ZnS: Cu, Al phosphor was used as the _second phosphor, and a ZnGa ₂ O ₄ : Mn phosphor was used as the first phosphor. Here, when the weight ratio of the first phosphor in the entire phosphor film to the total phosphor weight including the first and second and subsequent phosphors is x, x is changed from 0.1 to 0.9, The range of y was changed to (x + 0.1) ≦ y ≦ 1, where y represents the weight ratio of the first phosphor to the total weight of the outermost surface layer of the phosphor film on the energy input side.

Further, the ZnGa ₂ O ₄ : Mn phosphor having an average particle diameter of 3 μm to 4 μm was used, and the average particle diameter of the ZnS: Cu, Al phosphor was made smaller than 5 μm to 6 μm. In addition, as a comparison with the prior art, a phosphor film whose entire film is composed of ZnS: Cu, Al phosphor and a phosphor film whose entire film is composed of ZnGa ₂ O ₄ : Mn phosphor are also produced, Furthermore, a field emission display panel using these fluorescent films on the display surface was produced.

  As a result of performing the same measurement as in Example 1 and comparing these panels, it was shown that both the luminance and deterioration of the example of the present invention were superior to the phosphor film of the prior art.

  As described above, by using the present invention, it is possible to provide a fluorescent film and an image display device having high luminance and a long lifetime.

A fluorescent film having the structure shown in FIG. 1 was prepared by a method of applying two layers using a phosphor slurry. Using this phosphor film for the display surface, a field emission display panel having the structure shown in FIG. 2 was produced. A ZnS: Cu, Al phosphor was used as the _second phosphor, and a Y ₂ SiO ₅ : Tb phosphor was used as the first phosphor. Here, when the weight ratio of the first phosphor in the entire phosphor film to the total phosphor weight including the first and second and subsequent phosphors is x, x is changed from 0.1 to 0.9, The range of y was changed to (x + 0.1) ≦ y ≦ 1, where y represents the weight ratio of the first phosphor to the total weight of the outermost surface layer of the phosphor film on the energy input side.

In addition, as a comparison with the prior art, a fluorescent film in which the entire film is made of Y ₂ SiO ₅ : Tb phosphor and a fluorescent film in which the whole film is made of ZnS: Cu, Al phosphor are also produced, Furthermore, a field emission display panel using these fluorescent films on the display surface was produced. The average particle diameter of each phosphor was 5 μm to 6 μm.

  As a result of performing the same measurement as in Example 1 and comparing these panels, it was shown that both the luminance and deterioration of the example of the present invention were superior to the phosphor film of the prior art.

  As described above, by using the present invention, it is possible to provide a fluorescent film and an image display device having high luminance and a long lifetime.

A fluorescent film having the structure shown in FIG. 1 was prepared by a method of applying two layers using a phosphor slurry. Using this phosphor film for the display surface, a field emission display panel having the structure shown in FIG. 2 was produced. A ZnS: Ag, Al phosphor was used as the _second phosphor, and a CaMgSi ₂ O ₆ : Eu phosphor was used as the first phosphor. Here, when the weight ratio of the first phosphor in the entire phosphor film to the total phosphor weight including the first and second and subsequent phosphors is x, x is changed from 0.1 to 0.9, The range of y was changed to (x + 0.1) ≦ y ≦ 1, where y represents the weight ratio of the first phosphor to the total weight of the outermost surface layer of the phosphor film on the energy input side.

In addition, as a comparison with the prior art, a phosphor film in which the entire film is composed of CaMgSi ₂ O ₆ : Eu phosphor and a phosphor film in which the entire film is composed of ZnS: Ag, Al phosphor are also produced, Furthermore, a field emission display panel using these fluorescent films on the display surface was produced.

  As a result of performing the same measurement as in Example 1 and comparing these panels, it was shown that both the luminance and deterioration of the example of the present invention were superior to the phosphor film of the prior art.

  As described above, by using the present invention, it is possible to provide a fluorescent film and an image display device having high luminance and a long lifetime.

A fluorescent film having the structure shown in FIG. 1 was prepared by a method of applying two layers using a phosphor slurry. Using this phosphor film for the display surface, a field emission display panel having the structure shown in FIG. 2 was produced. A ZnS: Cu, Al phosphor was used as the _second phosphor, and a Y ₂ SiO ₅ : Tb phosphor mixed with 5% by weight of the conductive material In ₂ O ₃ was used as the first phosphor. As a comparison with the prior art, the entire film is made of a Y ₂ SiO ₅ : Tb phosphor mixed with 5% by weight of a conductive material In ₂ O ₃ , and the entire film is made of ZnS: Fluorescent films composed of Cu and Al phosphors were also fabricated, and a field emission display panel using these phosphor films on the display surface was fabricated. The average particle diameter of each phosphor was 5 μm to 6 μm.

  As a result of performing the same measurement as in Example 1 and comparing these panels, it was shown that both the luminance and deterioration of the example of the present invention were superior to the phosphor film of the prior art.

  As described above, by using the present invention, it is possible to provide a fluorescent film and an image display device having high luminance and a long lifetime.

  The fluorescent film included in the configuration of the present invention was applied to a plasma display panel (PDP). FIG. 3 shows the cell structure of the plasma display panel. FIG. 4 shows the configuration of the plasma display panel. A plasma display according to the present invention having such a structure was produced.

  As a result of evaluating the characteristics, the plasma display according to the present invention produced this time exceeded the conventional product in luminance. In addition, the image quality was equal to or better than the conventional product. That is, according to the present invention, an image display device with high brightness and good image quality was obtained.

It is the block diagram which showed typically the cross-section of the fluorescent film in this invention. It is a block diagram of the field emission type display panel in this invention. It is a cell structure figure of a plasma display panel. It is a structure of a plasma display panel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Face plate, 2 Transparent electrode, 3 2nd fluorescent substance layer, 4 1st fluorescent substance layer, 5 Face plate, 6 Transparent electrode, 7 Fluorescent film, 8 Rear plate, 9 Cathode, 10 resistance film, 11 Insulating film , 12 gate, 13 conical metal, 14 field emission electron source, 15 phosphor, 16 partition, 17 address electrode, 18 back substrate glass, 19 front substrate glass, 20 dielectric layer, 21 protective film MgO, 22 display electrode , 23 green phosphor layer, 24 red phosphor layer, 25 blue phosphor layer.

Claims (13)

In an image display device having a phosphor film in which phosphor particles are stacked, energy is applied to the phosphor film from one direction or a plurality of directions to excite the phosphor to emit light, and display is performed using the light. The film is composed of at least two kinds of phosphors, and the weight of the first phosphor in the entire phosphor film includes the first and second and subsequent phosphors, and the weight ratio to the total phosphor weight is x. Then, if the range of x is 0 <x ≦ 0.9 and the weight ratio of the first phosphor to the total weight of the outermost surface layer of the phosphor layer on the energy input side is y, the range of y is ( have a phosphor layer is x + 0.1) ≦ y ≦ 1 ,
The ratio of the luminance of the first phosphor after irradiating excitation energy for a certain time to the initial luminance is larger than the ratio of the second and subsequent phosphors,
The electrical resistivity of the first phosphor is a value different from the electrical resistivity of the second and subsequent phosphors;
The first phosphor is any one of ZnGa ₂ O ₄ : Mn and Y ₂ SiO ₅ : Tb, and the second phosphor is made of ZnS: Ag, Al, ZnO: Zn. Any one of the above, An image display device characterized by things. The image display device according to claim 1, wherein when the fluorescent film is observed from the energy input side using a scanning electron microscope or the like, the first fluorescent light according to claim 1 is formed on the outermost surface of the fluorescent film on the energy input side. When the ratio of the area occupied by the body to the area of the entire surface is a, the specific gravity of the first phosphor is u, and the average specific gravity of the entire phosphor including the first and second and subsequent phosphors is v , A has a fluorescent film with {(x + 0.1) v / u} ^2/3 ≦ a ≦ 1 with respect to the weight ratio x of claim 1. 2. The image display device according to claim 1, wherein the range of the weight ratio y with respect to the weight ratio x is (x + 0.1) ≦ y <1 . The image display device according to claim 2, wherein the range of the area ratio a to the weight ratio x is
{(X + 0.1) v / u} ^2/3 ≦ a <1 5. The image display device according to claim 1 , wherein the second and subsequent phosphors are phosphors having a composition containing an S element. 6. 5. The image display device according to claim 1 , wherein an average particle size of the first phosphor is smaller than an average particle size of second and subsequent phosphors. . 5. The image display device according to claim 1 , wherein an average particle size of the first phosphor is smaller than an average particle size of second and subsequent phosphors. . 5. The image display device according to claim 1, further comprising a conductive substance in addition to each phosphor. 5. The image display device according to claim 1, wherein an average particle diameter of the first phosphor is 3 to 4 μm, and an average particle diameter of the second phosphor is 5 to 6 μm. An image display device characterized by that. The image display device according to any one 請 Motomeko 1-9, the image display apparatus characterized by energy to be introduced into the phosphor is an electron beam. The image display device according to any one 請 Motomeko 1-9, the image display apparatus, characterized in that the electron beam energy is accelerated by voltages below 15kV to be introduced into the phosphor. The image display device according to 請 Motomeko 1-9 any one, an image display device, wherein the energy is in the ultraviolet light wavelength 380nm to be introduced into the phosphor. The image display device according to any one 請 Motomeko 1-9, the image display apparatus, wherein the energy is less of a vacuum ultraviolet wavelength 200nm to be introduced into the phosphor.

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