JP3945280B2 - Gas discharge panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas discharge panel typified by a plasma display panel (hereinafter abbreviated as PDP) and a method for manufacturing the same, and more particularly to an AC-driven gas discharge panel for PDP called a counter three-electrode surface discharge type.
[0002]
[Prior art]
The gas discharge panel for PDP is a flat display that displays an image by exciting phosphors with ultraviolet rays generated by gas discharge. It is classified into an alternating current (AC) type and a direct current (DC) type according to the discharge forming method. The AC type is superior to the DC type in terms of luminance, luminous efficiency, and lifetime. In particular, the reflective type surface discharge type stands out in terms of luminance and luminous efficiency, and this type is widely used. It's being used.
[0003]
A surface discharge AC gas discharge panel has a structure in which a front plate and a rear plate are bonded together with a discharge space, and a plurality of display electrode pairs are arranged on the front plate, and a dielectric layer is formed thereon. And a protective layer are formed. A plurality of address electrodes and barrier ribs are formed in parallel to the address electrodes on the back plate, and a phosphor layer is formed between the barrier ribs. The display electrode pair formed on the front plate and the address electrode formed on the back plate are bonded so as to be orthogonal to each other.
[0004]
In the AC drive type PDP, since the dielectric layer formed on the display electrode pair exhibits a specific current limiting function, the life can be extended as compared with the DC drive type PDP. Since this dielectric layer needs to be formed after the formation of the display electrode pair and the black matrix, and so as to securely cover them, generally a low melting point glass is printed and fired. Forming. The protective layer is provided to prevent the dielectric layer from being sputtered by plasma discharge, and is required to be a material excellent in sputtering resistance. For this reason, magnesium oxide (MgO) is often used. Since MgO has a large secondary electron emission coefficient (γ), it also has an effect of reducing the discharge start voltage.
[0005]
When the front plate and the back plate are opposed to each other, a striped discharge space is generated between the front plate and the back plate and surrounded by two partition walls. This space is filled with a mixed gas of neon (Ne) and xenon (Xe) to a pressure of about 66.5 kPa, and an AC voltage of several tens to several hundreds of kHz is applied between each pair of display electrodes for discharge. Then, the phosphor layer can be excited by ultraviolet rays generated when the excited Xe atoms return to the ground state. This excitation causes the phosphor layer to emit red (R light), green (G light), or blue (B light) depending on the applied material, so the pixel and color to be emitted by the address electrode can be selected. If it carries out, a required color can be emitted in a predetermined pixel part and a color image can be displayed.
[0006]
Such a gas discharge panel is required to be driven at a lower voltage and to have a high luminance. On the other hand, a method for reducing the discharge start voltage by using a discharge gas added with argon (Ar) in place of the commonly used discharge gas composed of Xe and Ne has been proposed. . This is a method of lowering the discharge start voltage by the Ar gas penning effect and improving the light emission luminance (Japanese Patent Laid-Open No. 2000-156164).
[0007]
[Problems to be solved by the invention]
In the image display, if the resolution is VGA (640 × 480) or higher, the higher the screen brightness, the more beautiful the displayed image. Also, if the screen brightness can be increased, the light contrast can be increased by slightly reducing the light transmittance of the front plate to suppress the reflection of external light, and a beautiful image can be displayed even in a light place. In order to increase the light emission luminance in the PDP, it is conceivable to increase the power to be input by increasing the driving voltage. However, since the drive voltage itself is originally high in the PDP, when the voltage is further increased, there are problems such as erroneous discharge or a high breakdown voltage of the driver circuit element, which increases the cost. Therefore, it is impossible to simply increase the driving voltage, and therefore, the bright place contrast is lower than that of the image display of the color cathode ray tube (CRT).
[0008]
In the above example, Ar is added to the discharge gas to reduce the discharge start voltage due to the Penning effect, and increase the discharge current even with the same drive voltage to achieve high brightness. That is, by lowering the discharge start voltage, the discharge current can be increased by that amount, so that the input power can be increased, and an image display with higher brightness can be obtained. However, when Ar is added, as is well known, since Ar has the property of easily sputtering the surface of the solid material, the MgO protective layer is sputtered and the surface is damaged. When such damage occurs, the secondary electron emission coefficient (γ) of the MgO protective layer decreases. As a result, deterioration with time occurs. For example, a drive operation for several thousand hours increases the discharge start voltage and decreases the luminance.
[0009]
The present invention has been made to solve the above-described problems, and realizes a high-reliability gas discharge panel for a PDP that realizes high luminance by reducing a discharge start voltage and hardly causes deterioration over time, and its manufacture. It aims to provide a method.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a gas discharge panel according to the present invention includes a front plate in which a plurality of display electrode pairs, a dielectric layer covering the display electrode pair, and a protective layer are formed on a transparent and insulating front substrate, A gas discharge panel configured such that at least a phosphor layer and a back plate having barrier ribs formed on a substrate are opposed to each other through a discharge space, wherein the protective layer is made up of groups II and VI of the periodic table The element is the main component, And containing Na or P as an additive element, In the film thickness direction from the dielectric layer side toward the discharge space side, the concentration of the additive element is smaller on the discharge space side than on the dielectric layer side.
[0011]
With this configuration, the proportion of electrons present on the discharge space side of the protective layer can be increased, and the secondary electron emission coefficient (γ) of the protective layer can be increased. As a result, a discharge start voltage is reduced and a high-intensity gas discharge panel is realized. Furthermore, since the proportion of electrons present on the discharge space side of the protective layer can be increased as compared to the conventional configuration, even if the protective layer is used for a long period of time, the γ is unlikely to change, and the reliability is high. A gas discharge panel is obtained.
[0012]
Further, the gas discharge panel of the present invention has a concentration of the additive element in the protective layer. Decreasing continuously or stepwise from the dielectric layer side toward the thickness direction on the discharge space side It has a configuration.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0020]
(First embodiment)
FIG. 1 is a perspective view of a main part of a PDP gas discharge panel according to the first embodiment, and FIG. 2 is a cross-sectional view taken along an address electrode.
[0021]
A display electrode pair 104, a black matrix 107, and a dielectric layer 105 are formed on the transparent and insulating front side substrate 101 so as to cover them, and a protective layer 106 is further formed on the dielectric layer 105. Thus, the front plate 100 is configured. The display electrode pair 104 is composed of a sustain electrode 102 and a scan electrode 103, which are composed of transparent conductive films 102a and 103a and bus electrodes 102b and 103b for further reducing wiring resistance. . The bus electrodes 102b and 103b are formed parallel to the transparent conductive films 102a and 103a, respectively, and are narrower than the transparent conductive films 102a and 103a. Such display electrode pairs 104 are formed on the front substrate 101 with a predetermined pitch and the required number of displays.
[0022]
The transparent conductive films 102a and 103a are made of indium tin oxide (ITO) or tin oxide (SnO). ₂ ) Or the like is formed by printing / firing or sputtering. Since this transparent conductive material alone cannot lower the resistance as an electrode, particularly in a large screen PDP, the power loss due to the conductive film is a value that cannot be ignored. In order to prevent this, the bus electrodes 102b and 103b are formed on the transparent conductive films 102a and 103a as a single-layer structure film such as low resistance silver, aluminum or copper, or a two-layer structure of chromium and copper, chromium, copper and chromium. Are formed by a thin film forming technique such as a printing / firing method or sputtering.
[0023]
For example, when ITO is formed as the transparent conductive films 102a and 103a by sputtering with a thickness of about 0.2 μm to 0.5 μm, the sheet resistance of the film is about 10Ω / □ to 25Ω / □. On the other hand, when silver is formed as the bus electrodes 102b and 103b by a printing method with a thickness of about 2 μm to 10 μm, the sheet resistance is about 1 mΩ / □ to 3 mΩ / □. Since the transparent conductive films 102a and 103a and the bus electrodes 102b and 103b are formed in parallel, the sheet resistance of the display electrode pair 104 is almost determined by the bus electrodes 102b and 103b and can be made sufficiently low.
[0024]
In the AC drive type PDP, since the dielectric layer 105 formed on the display electrode pair 104 exhibits a specific current limiting function, the life can be extended as compared with the DC drive type PDP. Since the dielectric layer 105 is required to be formed so as to securely cover the display electrode pair 104 and the black matrix 107, the low-melting-point glass is generally printed and printed. It is formed by a firing method. Examples of the glass paste material include lead oxide (PbO) and silicon oxide (SiO ₂ ), Boron oxide (B ₂ O _Three ), Zinc oxide (ZnO), barium oxide (BaO), etc., so-called (PbO—SiO) ₂ -B ₂ O _Three A low melting point glass paste having a -ZnO-BaO) glass composition can be used. By using this glass paste, for example, by repeating screen printing and firing, the dielectric layer 105 having a predetermined thickness can be easily obtained. This film thickness may be set according to the thickness of the display electrode pair 104, the target capacitance value, or the like. In the first embodiment, the film thickness is about 40 μm. Furthermore, PbO, bismuth oxide (Bi ₂ O _Three ) And phosphorus oxide (PO _Four You may use the glass paste which has as a main component at least 1).
[0025]
Further, as described above, the protective layer 106 is provided to prevent the dielectric layer 105 from being sputtered by plasma discharge, and is required to be a material having excellent sputtering resistance. For this reason, MgO is often used. The formation of the MgO film will be described in detail later.
[0026]
On the other hand, address electrodes 112 for writing image data are formed in a direction orthogonal to the display electrode pair 104 of the front plate 100 on the rear side substrate 111 which is similarly transparent and has an insulating property. A base dielectric layer 113 is formed on the surface of the back substrate 111 so as to cover the address electrode 112, and then a partition 114 is formed in parallel with the address electrode 112 and at substantially the center between the address electrodes 112, 112. In addition, the phosphor layer 115 is formed in a region sandwiched between the two barrier ribs 114 and 114 including the upper portion of the barrier ribs 114 and 114, thereby forming the back plate 110. As shown in FIG. 1, the phosphor layer 115 is formed by adjoining phosphor layers 115a, 115b, and 115c that emit R light, G light, and B light, and constitute a pixel. .
[0027]
The address electrode 112 can be formed by the same material and film formation method as the bus electrodes 102b and 103b of the front plate 100. In addition, the base dielectric layer 113 can be formed by the same material and film formation method as the dielectric layer 105, and further, PbO, Bi ₂ O _Three And PO _Four You may use the glass paste which has at least 1 of these as a main component. If the barrier rib 114 is formed by screen printing glass paste a plurality of times to a thickness of about 120 μm, the space surrounded by the barrier ribs 114 and 114 and having a height of about 120 μm becomes the discharge space 120. In addition, the phosphor layer 115 can be formed with phosphors that emit R light, G light, and B light, respectively, in the partition 114 portion by an inkjet method, for example.
[0028]
When the front plate 100 and the back plate 110 are made to face each other, a stripe shape surrounded by two partition walls 114 and 114, a protective layer 106 on the front substrate 101, and a phosphor layer 115 on the rear substrate 111, respectively. A discharge space 120 is created. The space 120 is filled with the above-described mixed gas of Ne and Xe so as to have a pressure of about 66.5 kPa, and several tens of kHz to several hundreds of kHz between the sustain electrode 102 and the scan electrode 103 via the respective bus electrodes 102b and 103b. When the alternating voltage is applied and discharged, the phosphor layer 115 can be excited by ultraviolet rays generated when the excited Xe atoms return to the ground state. By this excitation, the phosphor layer 115 emits R light, G light, or B light according to the applied material. Therefore, if a pixel to be emitted and a color are selected by the address electrode 112, a predetermined pixel portion Thus, a necessary color can be emitted and a color image can be displayed.
[0029]
In the state where the front plate 100 and the back plate 110 are opposed to each other, the adjacent discharge spaces 120 are shielded by the barrier ribs 114 and are designed to prevent erroneous discharge and optical crosstalk. Yes. Although not shown, the back plate 110 may be provided with a reflecting mirror so as to exhibit a high reflectance with respect to visible light (400 nm to 800 nm).
[0030]
Next, a method for manufacturing the protective layer 106 of the present invention will be described. FIG. 3 is a schematic explanatory diagram of an electron beam vapor deposition apparatus used for forming the protective layer 106 of the first embodiment. The inside of the bell jar 310 is connected to the vacuum pump 311 via the valve 312. After the front plate 100 having the dielectric layer 105 formed thereon is attached to the substrate holder 301, the valve 312 is opened to check the inside of the bell jar 310. The vacuum pump 311 is evacuated to a predetermined degree of vacuum. Below the bell jar 310, the first electron beam evaporation source 304, the second electron beam evaporation source 307, and the third electron beam evaporation source 309 are predetermined so as to ensure a uniform film thickness with respect to the front plate 100. It is arranged at an angle. Each electron beam evaporation source includes electron guns 302, 305, and 314, and hearths 303, 306, and 308 that hold evaporation substances that receive the electrons from the electron gun and are evaporated by heating. In each of the hearths 303, 306 and 308, MgO pellets which are Group II and Group VI elements are placed, and the MgO pellets installed in each Hearth are composed of Group I and Group V elements. The amount of at least one additional element selected is different. For example, in the present embodiment, an Na element is selected as the additive element, and the amount added to the MgO pellet is changed. That is, the MgO pellet 321 to which the Na is not added at all to the first electron beam evaporation source 304, the MgO pellet 322 to which the maximum concentration is added to the second electron beam evaporation source 307, and the third electron beam. In the evaporation source 309, MgO pellets 323 to which an amount of Na between the two is added are arranged in each hearth. As the Na source, not only metallic sodium but also a sodium compound can be used. Examples of sodium compounds include NaCl and NaNO. _Three , Na ₂ SO _Four , NaBO ₂ , Na ₂ B _Four O ₇ / 10H ₂ O, Na ₂ CO _Three NaHCO _Three Alternatively, NaOH or the like can be used.
[0031]
In this embodiment, the protective layer 106 of MgO having the Na concentration profile in the film thickness direction as shown in FIG. 4 was formed using such an electron beam evaporation apparatus. The MgO film having such a concentration profile is deposited by the second electron beam evaporation source 307 to a predetermined film thickness, and then deposited from the first electron beam evaporation source 304 to the final required film thickness. Can be easily obtained. In FIG. 4, the horizontal axis indicates the thickness of the protective layer in the depth direction, and the vertical axis indicates the concentration of Na. A gas discharge panel having such a protective layer 106 is referred to as Example 1.
[0032]
For comparison, as shown in FIG. 5, an MgO film having a constant Na concentration in the film thickness direction and an MgO film not added with Na were also formed and subjected to comparative evaluation as a gas discharge panel. . A gas discharge panel composed of a protective layer having a constant Na concentration is referred to as Comparative Example 1, and a gas discharge panel composed of a protective layer not added with Na is referred to as Comparative Example 2. The concentration distribution of Na was confirmed by performing secondary ion mass spectrometry (SIMS) on the MgO film formed on the Si wafer 315 arranged at the same distance as the front plate 100.
[0033]
For Example 1, Comparative Example 1 and Comparative Example 2, the same drive voltage waveform was applied to examine the discharge start voltage. As a result, 162V was obtained in Example 1, 177V in Comparative Example 1, and 175V in Comparative Example 2. On the other hand, when 177 V, which is the discharge start voltage of Comparative Example 1, was applied and the luminance in all white display was evaluated, in Example 1, 528 cd / m. ² In Comparative Example 1, 458 cd / m ² In Comparative Example 2, 468 cd / m ² Met. As can be seen from this result, it was found that the protective layer having the configuration of the present invention can reduce the discharge start voltage.
[0034]
At least one element selected from Group I and Group V elements is added to the protective layer made of Group II and Group VI elements, and the concentration of the added elements on the discharge space side is reduced. Thus, the present inventors consider that the discharge start voltage can be lowered as follows. That is, Na atoms enter the lattice position of Mg atoms in the MgO protective layer 106, thereby functioning as an acceptor. As shown in FIG. 4, a band structure as shown in FIG. 6 is obtained in the MgO protective layer by providing a concentration distribution in which the concentration of Na atoms is stepped and the concentration on the discharge space side is reduced. It is done. Accordingly, more electrons can exist on the surface of the protective layer 106 due to the diffusion potential generated inside the protective layer 106. As a result, it is considered that since the electron emission from the MgO surface as the protective layer 106 is further promoted, the discharge start voltage can be lowered.
[0035]
On the other hand, in Comparative Example 1 and Comparative Example 2, since the acceptor does not exist at the surface side of the protective layer 106 or does not exist at all, the diffusion potential as shown in FIG. There cannot be more electrons on the side. For this reason, the above operation cannot be obtained, and the discharge start voltage cannot be reduced. However, the discharge start voltage in Comparative Example 1 was slightly lower than that in Comparative Example 2 because Na atoms acted as an acceptor, and in the protective layer 106 than Comparative Example 2 in which Na atoms were not added. It is estimated that the number of electrons on the surface of a certain MgO film has decreased.
[0036]
Further, the gas discharge panel of Example 1 was subjected to an accelerated life test corresponding to 50,000 hours under normal use. However, the discharge start voltage and the light emission luminance were negligible, and could be operated very stably. confirmed. Furthermore, this panel was disassembled and the MgO film was observed, but it was confirmed that the film thickness was not reduced by sputtering with the discharge gas.
[0037]
In this embodiment, a mixed gas of Ne and Xe is used as the discharge gas. However, the present invention is not limited to this, and He is mixed with He that has a smaller mass number than Ar and has a small sputtering effect on the MgO film. May be used.
[0038]
(Second Embodiment)
The gas discharge panel of the second embodiment of the present invention has the same configuration as that of the first embodiment, but at least one selected from Group I and Group V elements in the film thickness direction. A protective layer in which the amount of the additive element was changed was formed. This is because a film having a desired distribution structure can be produced by changing the amount of addition of Na atom, which is an additive element in the MgO pellet, which becomes a protective layer material to be installed in the hearth by the vapor deposition apparatus as shown in FIG. A gas discharge panel in which the concentration distribution of Na atoms in the MgO film was changed as shown in FIGS.
[0039]
The protective layer having the distribution shown in FIG. 7A uses two electron beam evaporation sources each having a different Na atom addition amount, and first the second electron beam evaporation source 307 having the largest Na atom addition amount. Then, after forming the film until the final film thickness ratio is larger than 0.5, the shutter (not shown) is closed to completely stop the evaporation. After that, when a predetermined evaporation rate is confirmed by a monitor using the first electron beam evaporation source 304 to which no Na atom is added, a shutter (not shown) is opened to evaporate to a predetermined film thickness. Thus, the protective layer 106 having a sharp concentration distribution can be obtained.
[0040]
The protective layer having the distribution shown in FIG. 7B also uses two electron beam evaporation sources similar to the case of FIG. 7A, and the second electron beam evaporation source 307 having the largest amount of Na atoms is initially added. After evaporating until a predetermined film thickness is formed, the shutter is closed to completely stop vapor deposition. Next, the shutters of the first electron beam evaporation source 304 to which Na atoms are not added and the second electron beam evaporation source 307 having a large amount of addition of Na atoms are adjusted to have predetermined values. After adjusting with a monitor with the closed, the shutter is opened and deposition is started. After the deposition is started, the evaporation rate of the second electron beam evaporation source 307 is gradually decreased to obtain a protective layer having a concentration distribution as illustrated. Since the protective layer having the distribution shown in FIGS. 7C to 7E can also be easily obtained by combining the above methods, description thereof is omitted.
[0041]
The gas discharge panel having the protective layer with the five types of concentration distributions thus prepared was evaluated in the same manner as in the first embodiment. As a result, the discharge starting voltage was 156 V to 162 V for all the five types of panels. Luminance is 520cd / m ² ~ 550cd / m ² was gotten. Therefore, it was confirmed that any of these gas discharge panels has the same operation and effect as described in the first embodiment. This can be said to reinforce that many electrons can exist on the surface of the protective layer by the band structure described in the first embodiment.
[0042]
Here, the discharge start voltage of the gas discharge panel having the protective layer 106 having the concentration distribution shown in FIG. 7A is 156 V, and the gas discharge having the protective layer having the continuous concentration distribution as shown in FIG. An even lower discharge start voltage than that of the panel was obtained. This is because the position of the point (A) where the concentration greatly changes is located on the discharge space side, so that the region where electrons are confined can be narrowed, and more electrons are placed on the surface on the discharge space side. Because it came to exist.
[0043]
(Third embodiment)
In the third embodiment of the present invention, the protective layer 106 having P atoms selected from the group V as an additive element in the MgO film is used in the gas discharge panel fabricated in the first embodiment. The concentration distribution of P atoms in the MgO film was formed as shown in FIG. This MgO film can be easily produced by using the MgO pellet added with P atoms instead of Na in the pellet as the evaporation source in the electron beam vapor deposition apparatus described in the first embodiment. As the phosphorus source, metallic phosphorus or a phosphorus compound can be used. As a phosphorus compound, Ca _Three P ₂ , GaPNa, K _Three Metal phosphides such as P, (NH _Four ) ₂ HPO _Four , NH _Four H ₂ PO _Four , K _Three PO _Four , K ₂ HPO _Four , Ca _Three (PO _Four ) ₂ , CaHPO _Four , Ca (H ₂ PO _Four ) ₂ Fe _Three (PO _Four ) ₂ , FePO _Four Phosphates such as may be used. The concentration distribution of P atoms was also confirmed by performing SIMS analysis of a film formed on the Si wafer 315 disposed in the vicinity of the front plate 100. A gas discharge panel having such a protective layer is referred to as Example 3.
[0044]
As in the first embodiment, for comparison, a gas discharge panel having a protective layer 106 made of an MgO film having a constant P atom concentration in the film thickness direction as shown in FIG. A gas discharge panel having a protective layer 106 made of an MgO film not included was prepared in the same manner. A gas discharge panel made of a protective layer having a constant concentration of P atoms is called Comparative Example 3, and a gas discharge panel made of a protective layer to which no P atoms are added is called Comparative Example 4.
[0045]
When these three types of gas discharge panels were examined for the discharge start voltage using the same drive voltage waveform, they were 160 V in Example 3, 175 V in Comparative Example 3, and 173 V in Comparative Example 4. In addition, when the highest drive voltage of 175 V was applied and the luminance in all white display was evaluated, in Example 3, it was 530 cd / m. ² In Comparative Example 3, 460 cd / m ² And in Comparative Example 4, 470 cd / m ² Met.
[0046]
Thus, by providing the concentration distribution to the P atoms contained in the protective layer 106, the discharge start voltage can be reduced because the P atoms enter the lattice position of the O atoms in MgO and function as an acceptor. It is because. As a result, a band structure as shown in FIG. 6 is obtained as in the case of Na atoms, and more electrons are present on the surface of the protective layer 106 due to the diffusion potential generated inside the protective layer 106. As a result, electron emission from the surface of the MgO film as the protective layer 106 is further promoted, and as a result, the discharge start voltage is lowered.
[0047]
On the other hand, in Comparative Example 3 and Comparative Example 4, since the acceptor does not exist on the surface of the protective layer 106, the diffusion potential as shown in FIG. 6 is not formed. For this reason, it becomes difficult for electrons to be collected on the surface of the protective layer on the discharge space side, and the above-described effect does not appear. However, the reason why the discharge start voltage is slightly higher in Comparative Example 3 than in Comparative Example 4 is that, as in the first embodiment, P atoms act as acceptors and are rather MgO compared to the case where P atoms are not included. This is because the number of electrons on the film surface decreases.
[0048]
Further, when an accelerated life test corresponding to continuous operation for 50,000 hours was performed in Example 3 for Example 3, the discharge start voltage was not significantly changed and was stable. Furthermore, when this panel was broken and the MgO film was observed, it was confirmed that there was almost no decrease in film thickness due to sputtering. The discharge gas is not limited to the mixed gas of Ne—Xe, and may be used by mixing He with less sputtering effect of the MgO film.
[0049]
(Fourth embodiment)
In the fourth embodiment of the present invention, a gas discharge panel comprising a protective layer 106 containing MgO as a main component and varying the concentration distribution of P atoms in the film was produced. The concentration distribution of P atoms in the protective layer 106 was set to a distribution form shown in FIGS. The protective layer having such a distribution is the same as the electron beam evaporation apparatus described in the second embodiment, in which a pellet in which an appropriate amount of phosphorus is added to the MgO pellet is disposed, Since it can be easily obtained by the vapor deposition method as described, the description is omitted.
[0050]
For the gas discharge panel composed of these five types of protective layers, the same evaluation as described in the first embodiment was performed. As a result, all the gas discharge panels have a discharge start voltage in the range of 155V to 163V, and the emission luminance is 521 cd / m. ² ~ 554cd / m ² The same performance as in Example 3 was obtained. Similarly to the second embodiment, in the case of the protective layer having the concentration distribution as shown in FIG. 7A, the discharge start voltage is the lowest, and the position of the point (A) where the concentration greatly changes is discharged. It was also confirmed that it is effective to provide the space side.
[0051]
In the first to fourth embodiments, the MgO film has been described as the protective layer 106. However, the present invention is not limited to this, and the elements of the Group II of the periodic table and the Group VI of the periodic table. If it is a compound consisting of these elements, the same effect and action can be obtained. For example, calcium oxide (CaO), BaO, cerium oxide (CeO) ₂ ) Etc. may be used.
[0052]
Further, the group I element of the periodic table distributed in the protective layer 106 is not limited to Na, and lithium (Li), potassium (K), rubidium (Rb), cesium (Cs), etc. are used alone. Or you may use two or more. The group V element in the periodic table is not limited to P, and nitrogen (N), arsenic (As), antimony (Sb), bismuth (Bi), or the like may be used alone or in combination. . Further, both the above Group I element and Group V element may be added to the protective layer 106. The effect of these additive elements as an acceptor is further synergized, and the efficiency of secondary electron emission can be further improved.
[0053]
In the first to fourth embodiments, the protective layer is formed by the electron beam vapor deposition apparatus. However, the present invention is not limited to electron beam vapor deposition, and may be produced by ion plating, sputtering, or the like. Good. In the case of producing by sputtering, a plurality of targets with different concentrations of additive elements are arranged in a horizontal direction, and a predetermined addition is performed by forming a film while moving the front plate horizontally on these targets. A protective layer having an element concentration distribution can be easily formed. Further, the electron beam vapor deposition apparatus may be configured such that a plurality of electron beam evaporation sources are arranged in the horizontal direction, and the film is formed while moving the substrate on these evaporation sources in the horizontal direction.
[0054]
Note that the amount of the additive element added to the protective layer 106 is 0.0001 atomic% or more, and 20 atomic% is a desirable amount capable of obtaining the characteristics of the present invention without impairing the crystallinity of the film.
[0055]
【The invention's effect】
The gas discharge panel of the present invention includes at least one additive element selected from Group I and Group V of the Periodic Table in the protective layer having Periodic Table Group II and Group VI as main components. The additive element has a configuration in which the concentration on the discharge space side is smaller than that on the dielectric layer side in the film thickness direction from the dielectric layer side to the discharge space side. As a result, the proportion of electrons present on the discharge space side in the protective layer can be increased, so that the secondary electron emission coefficient (γ) of the protective layer can be increased. Therefore, the discharge start voltage can be reduced, the brightness can be increased, and a great effect can be obtained that a gas discharge panel that is bright and has a high contrast even in a bright place can be realized.
[Brief description of the drawings]
FIG. 1 is a perspective view of a main part of a gas discharge panel according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of the main part of the gas discharge panel of the same embodiment
FIG. 3 is a schematic explanatory view of an electron beam evaporation apparatus for forming a protective layer in the embodiment.
FIG. 4 is a view showing the distribution in the film thickness direction of the additive element in the protective layer of the embodiment;
5 is a graph showing the distribution in the film thickness direction of additive elements in the protective layers of Comparative Example 1 and Comparative Example 3. FIG.
FIG. 6 is a schematic diagram for explaining a band structure of the protective layer of the embodiment;
FIG. 7 is a view showing the distribution in the film thickness direction of additive elements in the protective layer according to the second and fourth embodiments of the present invention;
[Explanation of symbols]
100 Front plate
101 Front side board
102 Sustain electrode
102a, 103a transparent conductive film
102b, 103b bus electrode
103 scan electrode
104 Display electrode pair
105 Dielectric layer
106 Protective layer
107 black matrix
110 Back plate
111 Back side substrate
112 Address electrode
113 Underlying dielectric layer
114 Bulkhead
115 phosphor layer
115a Phosphor layer (R light)
115b Phosphor layer (G light)
115c Phosphor layer (B light)
120 Discharge space
301 Substrate holder
302,305,314 Electron gun
303,306,308 Hearth
304 first electron beam evaporation source
307 Second electron beam evaporation source
309 Third electron beam evaporation source
310 Berja
311 Vacuum pump
312 valve
315 Si wafer
321,322,323 pellets

Claims (2)

A front plate in which a plurality of display electrode pairs, a dielectric layer covering them and a protective layer are formed on a transparent and insulating front side substrate, and at least a phosphor layer and a barrier rib are formed on the back side substrate. A gas discharge panel configured to face a back plate through a discharge space,
In the film thickness direction from the dielectric layer side toward the discharge space side, the protective layer contains the elements of Group II and Group VI of the periodic table as main components and contains Na or P as an additive element. A gas discharge panel wherein the element concentration is smaller on the discharge space side than on the dielectric layer side. 2. The gas according to claim 1, wherein the concentration of the additive element in the protective layer decreases continuously or stepwise from the dielectric layer side toward the thickness direction on the discharge space side. Discharge panel.

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