JP4337385B2 - Gas discharge panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas discharge panel having a phosphor layer that is used for image display of a television or the like and is excited by vacuum ultraviolet rays to emit light, and more particularly to a plasma display panel (hereinafter referred to as PDP).
[0002]
[Prior art]
In recent years, in color display devices used for image display such as computers and televisions, plasma display devices using PDPs have attracted attention as color display devices that can be large, thin, and lightweight.
[0003]
The PDP is a display that displays an image by exciting and emitting phosphors with ultraviolet rays generated by gas discharge.
[0004]
FIG. 4 shows a basic configuration of a discharge cell of a conventional reflective AC surface discharge PDP. The structure and operation will be described below.
[0005]
On the display surface side substrate 801 made of a glass plate, transparent electrodes 802X and 802Y made of ITO or SnO ₂ are formed in pairs. However, since the transparent electrodes 802X and 802Y have a high sheet resistance, and a large panel cannot supply sufficient power to all pixels, a thick silver film, an aluminum thin film, a chromium / chrome film is formed on the transparent electrodes 802X and 802Y, respectively. Bus electrodes 803X and 803Y made of a laminated thin film of copper / chromium (Cr / Cu / Cr) are formed. The bus electrodes 803X and 803Y apparently lower the sheet resistance of the transparent electrodes 802X and 802Y. A transparent dielectric layer (low melting glass is used) 804 and a protective layer 805 made of magnesium oxide (MgO) are formed on these electrodes. The dielectric layer 804 has a current limiting function peculiar to the AC type PDP, and is a factor that can make the life longer than that of the DC type. The protective layer 805 is provided to protect the dielectric layer 804 from being sputtered and removed by discharge, and has a high secondary electron emission coefficient (γ) and a high discharge start voltage. Reduction work is required.
[0006]
Opposite to the display surface side substrate 801, a back side substrate 806 made of a glass plate is provided. A data electrode 807 for writing image data, a base dielectric layer 808, a partition 809, and a phosphor layer 810 are formed on the back substrate 806.
[0007]
The PDP performs full color display by additively mixing so-called three primary colors (red, green, and blue). In order to perform this full-color display, the PDP is provided with a phosphor layer 810 that emits each of the three primary colors red (R), green (G), and blue (B), and constitutes the phosphor layer 810. The phosphor material is excited by ultraviolet rays generated in the discharge cell of the PDP, and generates visible light of each color.
[0008]
The phosphor layer 810 is formed on the back substrate 806 by forming the barrier ribs 809 and then applying phosphor paste of red (R), green (G), and blue (B) by screen printing or line jet method. After that, it is fired in the air to remove the solvent component in the paste.
[0009]
A glass frit for sealing is applied (not shown) around one or both of the display surface side substrate 801 and the back side substrate 806 configured as described above, and the resin component in the frit After removing the substrate by calcining at 300 to 350 ° C. and superimposing both substrates, they are heated to a high temperature (450 to 550 ° C.) to soften the sealing glass and bond the two substrates together (sealing process) ). Here, the data electrode 807 and the partition 809 are arranged so as to be orthogonal to the transparent electrodes 802X and 802Y, and in a space surrounded by the two partitions 809, the display surface side substrate 801, and the back side substrate 806. Thus, a discharge cell 811 is formed. At this time, the barrier ribs 809 function as partitions between adjacent discharge cells to prevent erroneous discharge and optical crosstalk.
[0010]
An AC voltage of several tens of kHz to several hundreds of kHz is applied between the transparent electrodes 802X and 802Y of the PDP to generate a discharge in the discharge cell 811, and vacuum ultraviolet rays (wavelengths: 147 nm, 173 nm from excited Xe atoms). ) To excite the phosphor layer 810 and generate visible light to perform a display operation.
[0011]
Here, the PDP has a problem that the operating voltage increases with time. This is because a hydrocarbon gas (hereinafter referred to as a CH gas) is adsorbed on the phosphor as an impure gas, and the CH gas is released into the discharge space by vacuum ultraviolet rays or ion bombardment generated by the discharge. This is a phenomenon that occurs because the secondary electron emission coefficient on the MgO surface decreases due to adsorption to the protective layer 805.
[0012]
Conventionally, in order to suppress an increase in operating voltage due to the CH-based gas, a technique has been proposed in which the surface of the MgO protective layer 805 is coated with a silicon compound or a silicon compound gas is mixed with a discharge gas (for example, a patent). Reference 1).
[0013]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-373588
[Problems to be solved by the invention]
The method of coating the surface of the MgO protective layer with a silicon compound is to react a CH-based gas with a silicon compound to decompose the CH-based gas into H ₂ O or CO ₂ , selectively in a region that does not affect the discharge. Is intended to generate. Since the silicon compound has a smaller secondary electron emission coefficient (γ) than MgO, the operating voltage is increased and the discharge stability is also deteriorated. Therefore, in the case of an optimal silicon compound or more, it is necessary to remove the silicon compound by a long discharge operation called aging in the PDP manufacturing process. At this time, most of the silicon compound is removed by sputtering on the MgO surface accompanying discharge, but cannot be completely removed because the removed silicon compound grows again on the MgO surface. Due to this influence, there is a problem that the secondary electron emission coefficient (γ) on the MgO surface becomes small, and the operating voltage does not drop sufficiently.
[0015]
The same applies when the silicon compound gas is mixed with the discharge gas. Since the SiC film produced by reaction with the CH gas also grows on the MgO surface, the secondary electron emission coefficient on the MgO surface is also reduced, and the operating voltage is increased. There is a problem of becoming.
[0016]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a stable gas discharge panel that does not increase in operating voltage over time.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, the gas discharge panel of the present invention has a display surface side substrate and a back side substrate that are opposed to each other through a discharge space, and is excited and emitted by at least a conductive electrode and ultraviolet light on the back side substrate. In the gas discharge panel in which the phosphor layer and the barrier rib are formed, a photocatalyst material layer is disposed in a discharge cell formed by the display surface side substrate, the back side substrate and the barrier rib, and the photocatalyst material layer is disposed on the photocatalyst material layer. An oxide layer is formed on the oxide layer, and a phosphor layer is formed on the oxide layer , and the photocatalytic substance layer includes titanium oxide, tin oxide, zinc oxide, dibismuth trioxide, tungsten trioxide, and ferric oxide. In addition, at least one of strontium titanate, or a mixture of two or more thereof is characterized. By irradiating the photocatalytic substance with ultraviolet light generated by the discharge in the cell, the CH-based gas is decomposed into CO ₂ or H ₂ O which is adsorbed on the MgO surface and does not cause a large fluctuation in operating voltage. A stable gas discharge panel without increasing the operating voltage can be realized. When the photocatalyst material layer is disposed on the partition walls of the discharge cell, the photocatalyst material layer can be disposed over a wide area in the discharge space, so that the effect is particularly high.
[0018]
Furthermore, in the gas discharge panel of the present invention, by forming an oxide layer on the photocatalyst material layer, the amount of hydroxy radicals (OH) generated by ultraviolet irradiation is increased, and the decomposition of the CH gas can be further promoted. Is.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a gas discharge panel according to an embodiment of the present invention will be described with reference to the drawings. In the following description, a PDP that is a typical example of a gas discharge panel will be described as an example.
[0020]
FIG. 1 is a cross-sectional perspective view showing a configuration of a PDP in Embodiment 1 of the present invention. FIG. 2 is a sectional view taken along the line AA ′.
[0021]
1 and 2, display electrodes 102X and 102Y made of a transparent conductive material such as ITO or tin oxide (SnO ₂ ) are formed on a display surface side substrate 101 made of a glass plate, and silver (Ag) is formed thereon. Bus electrodes 103X and 103Y made of a thick film (thickness: 2 μm to 10 μm), an aluminum (Al) thin film (thickness: 0.1 μm to 1 μm) or a Cr / Cu / Cr laminated thin film (thickness: 0.1 μm to 1 μm) are formed. is doing. Further covering 70% by weight of lead oxide (PbO), 15% by weight of boron oxide (B ₂ O ₃ ), and 15% by weight of silicon oxide (SiO ₂ ) so as to cover these display electrodes 102X and 102Y and bus electrodes 103X and 103Y. A dielectric layer 104 made of low-melting glass (thickness 20 μm to 40 μm) having a composition is formed by screen printing, die coating printing, or film laminating. Subsequently, a protective layer 105 (thickness: 0.3 μm to 1 μm) made of MgO for protecting the dielectric layer 104 from damage due to discharge plasma is formed by an electron beam evaporation method, a sputtering method, or a chemical vapor deposition method (CVD method). Is formed. Here, a display electrode of one pixel (pixel: PU) is constituted by two display electrodes 102X and 102Y arranged in parallel with each other at a predetermined interval, and an alternating voltage is applied between them to enter the discharge space 111. Generate a discharge.
[0022]
On the other hand, a back substrate 112 facing the display surface substrate 101 through the discharge space 111 is provided. The back substrate 112 is made of a glass plate, on which a silver (Ag) thick film (thickness: 2 μm to 10 μm), an aluminum (Al) thin film (thickness: 0.1 μm to 1 μm), or a Cr / Cu / Cr laminated thin film ( A base conductive electrode 107 having a thickness of 0.1 μm to 1 μm is formed, and a base dielectric layer 108 (thickness: 5 μm to 20 μm) made of low-melting glass is formed so as to cover the base conductive electrode 107. . Further, partition walls 109 (height 0.1 mm to 0.15 mm) are formed at predetermined intervals by repeating screen printing of low melting point glass and firing.
[0023]
Furthermore, a photocatalytic substance is disposed by forming a photocatalytic substance layer 120 having a thickness of 5 nm to 500 nm on the partition wall 109 and the base dielectric layer 108. The photocatalytic material layer 120 is formed by sputtering a titanium oxide (TiO ₂ ) film (a target is titanium oxide, and a sputtering gas is a mixed gas of Ar and O ₂ ).
[0024]
Further, an oxide layer 121 is formed on the photocatalytic substance layer 120 having a thickness of 5 nm to 200 nm. The oxide layer 121 is formed by sputtering a silicon oxide (silica: SiO ₂ ) film by a sputtering method (a target is silicon oxide, and a sputtering gas is a mixed gas of Ar and O ₂ ).
[0025]
Subsequently, phosphor layers 110R, 110G, and 110B of three primary colors (red: R, green: G, blue: B) for color display are sequentially stacked.
[0026]
The display surface side substrate 101 and the back side substrate 112 are bonded so that the display electrode 102 and the base conductive electrode 107 are orthogonal to each other, and the discharge cells partitioned by the partition 109 in the line direction for each subpixel SU, and thereby A partitioned discharge space 111 is formed. By aligning the heights of the barrier ribs 109, the gap dimension of the discharge space 111 takes a predetermined constant value. Here, one pixel (pixel: PU) is composed of three sub-pixels SU that emit light in the colors of red (R), green (G), and blue (B) side by side in the line direction.
[0027]
As described above, the display surface side substrate 101 and the back surface side substrate 112 are opposed to each other, the periphery is hermetically sealed, the inside of the discharge space 111 is evacuated while heating, and then a discharge gas composed of, for example, a mixed gas of Ne and Xe. At a predetermined pressure and mixing ratio. Further, 300 V to 500 V voltage pulses are alternately applied between the display electrodes 102X and 102Y to generate a discharge in the discharge space 111 between the display electrodes 102X and 102Y, and aging is performed to reduce and stabilize the discharge start voltage. PDP100 is produced by performing for 16 hours.
[0028]
Here, as a method for forming the photocatalytic material layer 120, in addition to the above sputtering method, an electron beam evaporation method in an oxygen atmosphere using metal titanium or titanium oxide as a source may be used. In order to stabilize the film, annealing may be performed at 200 ° C. to 600 ° C. after the film is formed.
[0029]
In addition to the above, the photocatalytic material layer 120 may be formed by diluting hydrochloric acid or ethylamine as a hydrolysis inhibitor with titanium alkoxide, titanium chelate or titanium acetate with ethanol or propanol as a diluent. Add a partially or completely hydrolyzed mixture, or an acidic aqueous solution of titanium tetrachloride or titanium sulfate (alkaline aqueous solution may be added if necessary), titanium oxide sol, etc., and spray A method of forming a titanium oxide layer by applying and drying by a technique such as coating, dip coating, flow coating, spin coating, roll coating, or the like, and baking at 200 ° C. to 600 ° C. can be used.
[0030]
As a method for forming the oxide layer 121 formed on the photocatalytic material layer 120, in addition to the above sputtering method, silicon or silicon oxide may be used as a source and an electron beam evaporation method may be used in an oxygen atmosphere. In order to stabilize the film, annealing may be performed at 200 ° C. to 600 ° C. after the film formation. Other formation methods include hydrolysis to tetraalkoxysilane (for example, tetraethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane, tetrabutoxysilane, tetramethoxysilane), silicon chelate, or silicon acetate. Hydrochloric acid or ethylamine as an inhibitor, diluted with ethanol or propanol as a diluent, and added to a partially or completely hydrolyzed mixture, or an acidic aqueous solution of titanium tetrachloride or titanium sulfate (necessary) (Alkaline aqueous solution may be added depending on the conditions) or a titanium oxide sol is prepared, applied, dried, and baked (200 ° C. to 600 ° C.) by techniques such as spray coating, dip coating, flow coating, spin coating, and roll coating. ) To a method of forming a silicon oxide (silica) layer can be used.
[0031]
For comparison, in the PDP 100, the photocatalyst material layer 120 and the oxide layer 121 were not formed, and other components were made exactly the same as the PDP 100, and a comparative PDP (A) was produced.
[0032]
The PDP 100 and PDP (A) were subjected to an accelerated life test corresponding to 50,000 hours in normal use. In the PDP 100, the discharge start voltage was changed only to the extent that there was almost no problem in operation, and it was confirmed that the PDP 100 can operate very stably during this period. On the other hand, in the case of the comparative PDP (A), the discharge start voltage was several volts higher than that of the PDP 100 even before the life test, but the discharge start voltage at the lighting section increased by 20 V or more over time even during the life test. In an accelerated life test corresponding to 10,000 hours in normal use, it was confirmed that a non-lighting area was generated in a part of PDP (A).
[0033]
After the life test, when these PDPs were divided and subjected to time-traveling secondary ion mass spectrometry (TOF-SIMS) on the surface of the MgO protective layer, the amount of adsorption of the CH-based gas of PDP (A) was larger than that of PDP100. It has been found. Further, when a part of the display surface side substrate and the back side substrate were cut out and subjected to temperature programmed desorption mass spectrometry (TDS), the CH of PDP (A) was compared with PDP 100 as in the case of TOF-SIMS. It was found that the amount of adsorption of the system gas was large. Furthermore, when TOF-SIMS analysis of the MgO surface was performed in the same manner before and after aging, it was found that the amount of adsorption of the CH-based gas was larger in PDP (A) than in PDP 100, although not as after the life test.
[0034]
In the PDP 100 according to the present invention in which the photocatalyst material layer 120 and the oxide layer 121 are formed on the barrier rib 109, the reason why the discharge start voltage is stable and has a long lifetime is considered as follows. The CH-based gas inside the PDP 100 is mainly adsorbed and taken in by the phosphor layer 110. When the PDP 100 is operated, the adsorbed CH-based gas is desorbed and adsorbed on the MgO surface due to ultraviolet irradiation or ion collision on the phosphor surface with discharge in the cell. Therefore, the secondary electron emission coefficient (γ) value decreases, and as a result, the discharge start voltage increases. The fact that the discharge start voltage of PDP (A) is larger than PDP100 after aging and that the discharge start voltage increased in the life test of PDP (A) seems to be caused by CH gas from the results of TOF-SIMS and TDS. .
[0035]
On the other hand, in the PDP 100 according to the present invention in which the photocatalytic material layer 120 is formed, the CH-based gas is changed to CO ₂ or H ₂ O which does not significantly affect the discharge start voltage due to the catalytic action of the photocatalytic material layer 120. Compared to the change in the discharge start voltage, the amount of CH-based gas is considered to be small in TOF-SIMS and TDS analysis.
[0036]
The decomposition of the CH gas in the photocatalytic material layer 120 will be described in a little more detail.
[0037]
When the surface of the photocatalytic substance layer 120, which is a semiconductor, is irradiated with ultraviolet rays generated by discharge in the cell, electrons are excited by the conductor and electron-hole pairs are generated. At this time, if the oxide layer 121 is formed on the photocatalytic substance layer 120, holes easily move to the oxide layer 121 and decompose H ₂ O adsorbed on the surface of the oxide layer 121. To generate hydroxy radicals (OH). This hydroxy radical (OH) undergoes an oxidation reaction with the CH-based gas existing on and near the surface of the oxide layer 121 and decomposes into CO ₂ and H ₂ O. Here, when the oxide layer 121 is made of a material that is more likely to adsorb more H ₂ O on the surface than the photocatalytic substance layer 120, the generation amount of hydroxy radicals (OH) increases, so that the decomposition of the CH-based gas can be further promoted. .
[0038]
By operating the PDP in this way, it is possible to decompose the CH-based gas by the ultraviolet rays generated inside and the photocatalytic material layer, and the CH-based gas gradually emerging from the phosphor surface increases the discharge start voltage. Since it decomposes into difficult CO ₂ and H ₂ O gas, stable operation becomes possible.
[0039]
Ultraviolet rays generated by discharge and having an action of exciting the phosphor have a high reflection coefficient on the phosphor surface and travel while reflecting between the phosphor particles in the phosphor layer 110, so that even under the phosphor layer 110. Ultraviolet rays reach the photocatalytic material layer 120 sufficiently. Therefore, the thickness of the oxide layer 121 formed on the surface of the photocatalytic substance layer 120 is preferably set in a range of 5 nm to 200 nm where absorption of ultraviolet rays is small.
[0040]
As those that can be used in the oxide layer _{121, SiO 2, V 2 O} 5, MoO 3, Ta 2 O 5, Nb 2 O 3, TiO 2, SnO 2, GeO 2, Fe 2 O 3 in addition to the silica , B ₂ O ₃ , As ₂ O ₃ , MgO, ZnO, PbO, Eu ₂ O ₃ , Nd ₂ O ₃ , TmO ₃ , Dy ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , Al ₂ O ₃ , Tl ₂ O ₃ , In ₂ O ₃ , Bi ₂ O ₃ , HfO ₂ , CoO, CuO, NiO, Ga ₂ O ₃ , MnO ₂ , CeO ₂ , Cr ₂ O ₃ , MgAlO ₄ , K ₂ O · Al ₂ O _{At least one of 3} · 6SiO ₂ , Na ₂ O · Al ₂ O ₃ · 6SiO ₂ , CaO · Al ₂ O ₃ · 6SiO ₂ , Sc ₂ O ₃ , or a mixture of two or more types can be used. In particular, when these materials are amorphous, oxygen atoms are relatively difficult to appear on the surface, and the H ₂ O adsorptivity is further increased, which is more preferable. In the case of amorphous, the layer may be out of the quantum composition or may contain hydrogen atoms or halogen (F, Cl, Br, I) atoms in the layer. These oxide layers 121 can be formed by a thin film forming process such as sputtering, vapor deposition, chemical vapor deposition (CVD), plasma CVD, etc., in addition to coating and drying of these metal alkoxides.
[0041]
The photocatalytic material constituting the photocatalytic substance layer 120 includes at least one of titanium oxide, tin oxide, zinc oxide, dibismuth trioxide, tungsten trioxide, ferric oxide, and strontium titanate, or Two or more types of mixtures can be used.
[0042]
FIG. 3 is a cross-sectional view showing a configuration of a PDP according to another embodiment of the present invention . The PDP 300 of the present embodiment does not have the base dielectric layer 108 in the PDP 100 (FIG. 2) shown in the above embodiment , and the other configuration is the same as that of the PDP 100.
[0043]
When this PDP 300 was subjected to a life test in the same manner as in the above-described embodiment, it was confirmed that, as with the PDP 100, the discharge start voltage change was small and the operation was stable.
[0044]
In the above embodiment, as the discharge gas, a mixed gas of He—Xe may be used in addition to a mixed gas of Ne—Xe, and Ar, Kr, or He may be added to these gases. . In addition, for these discharge gases, oxygen, NO, NO ₂ , N ₂ O, N ₂ O ₃ , N ₂ O ₄ , N ₂ O ₅ , NO _{3 and} other gases containing oxygen atoms in the molecule are used for PDP operation. Even if it is mixed to the extent that there is no influence (specifically 0.1 vppm to 10 vppm), it is effective because hydroxy radicals (OH) are generated by the photocatalytic action of the photocatalytic substance layer, and the decomposition of the CH gas can be further promoted. is there.
[0045]
【The invention's effect】
As described above, according to the present invention, the formation of the photocatalyst material layer in the discharge cell can decompose the CH-based gas that causes unstable operation over time, so that there is no change in voltage over time and operation. Can provide a highly stable gas discharge panel.
[Brief description of the drawings]
[1] Another embodiment of the present A-A 'sectional view of figure 1 showing a cross-sectional perspective view FIG. 2 structure of the PDP illustrating the structure of a PDP in accordance with an exemplary embodiment of the invention the present invention; FIG FIG. 4 is a cross-sectional perspective view showing the structure of a conventional PDP.
100 PDP
101 Display surface side substrate 102 Display electrode 103 Bus electrode 104 Dielectric layer 105 Protective layer 107 Underlying conductive electrode 108 Underlying dielectric layer 109 Partition 110R Phosphor layer (red)
110G phosphor layer (green)
110B phosphor layer (blue)
111 Discharge space 112 Back side substrate 120 Photocatalyst material layer 121 Oxide layer

Claims (2)

A gas discharge panel having a display surface side substrate and a back side substrate facing each other through a discharge space, wherein at least a conductive electrode, a phosphor layer excited by ultraviolet rays and a partition wall are formed on the back side substrate. A photocatalyst material layer is disposed in a discharge cell formed by the display surface side substrate, the back side substrate and the barrier ribs, an oxide layer is formed on the photocatalyst material layer, and the oxide layer is formed on the oxide layer. Forming a phosphor layer , and the photocatalytic substance layer is at least one of titanium oxide, tin oxide, zinc oxide, dibismuth trioxide, tungsten trioxide, ferric oxide, strontium titanate, or A gas discharge panel comprising two or more kinds of mixtures . The oxide layer is composed of SiO ₂ , V ₂ O ₅ , MoO ₃ , Ta ₂ O ₅ , Nb ₂ O ₃ , TiO ₂ , SnO ₂ , GeO ₂ , Fe ₂ O ₃ , B ₂ O ₃ , As ₂ O ₃ , MgO, ZnO, PbO, Eu ₂ O ₃ , Nd ₂ O ₃ , TmO ₃ , Dy ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , Al ₂ O ₃ , Tl ₂ O ₃ , In ₂ O ₃ , Bi _{2 O 3, HfO 2, CoO} , CuO, NiO, Ga 2 O 3, MnO 2, CeO 2, Cr 2 O 3, MgAlO 4, K 2 O · Al 2 O 3 · 6SiO 2, Na 2 O · Al 2 _{O 3 · 6SiO 2, CaO ·} Al 2 O 3 · 6SiO 2, Sc 2 O 3 gas discharge panel according to claim 1, characterized in that the invention will include any one or more of the.

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