JP2009004150A - Plasma display panel and manufacturing method thereof - Google Patents

Abstract

A plasma display panel with improved discharge characteristics is provided.
A plasma display panel (200) includes a first panel (1) and a second panel (8), and a discharge space (14) is formed between the first panel (1) and the second panel (8). A metal oxide 20 is disposed so as to face the discharge space 14, and the metal oxide 20 has a rock salt type crystal structure and is made of at least one element selected from the group consisting of Ca, Sr and Ba. The plasma display panel 200 is a solid solution of an oxide and an oxide of at least one element selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn.
[Selection] Figure 3

Description

  The present invention relates to a plasma display panel (PDP) and a manufacturing method thereof.

  Plasma display panels (hereinafter abbreviated as PDPs) have been put into practical use and are rapidly becoming popular among thin display panels because they are easy to enlarge, capable of high-speed display, and low cost.

  A general PDP structure currently in practical use is provided with a pair of regularly arranged electrodes on two opposing glass substrates on the front side and the back side, respectively, and covers these electrodes. Thus, a dielectric layer such as a low melting point glass is provided. A phosphor layer is provided on the dielectric layer of the rear substrate, and the dielectric layer is protected against ion bombardment on the dielectric layer of the front substrate, and as a protective layer for the purpose of secondary electron emission, An MgO layer is provided. A gas mainly composed of an inert gas such as Ne or Xe is sealed between the two substrates, and a voltage is applied between the electrodes to generate a discharge, thereby causing the phosphor to emit light and display.

  In the PDP, high efficiency is strongly demanded. As the means, a method of reducing the dielectric constant of the dielectric layer and a method of increasing the Xe partial pressure of the discharge gas are known. However, when such a means is used, there is a problem that the discharge start voltage and the sustain voltage increase.

On the other hand, it is known that as a material used for the protective layer, a material having a higher secondary electron emission coefficient is used, the discharge start voltage and the sustain voltage can be lowered. It is possible to realize low cost by using. For this reason, it has been studied to use CaO, SrO, BaO, which are the same alkaline earth metal oxides instead of MgO, but have a higher secondary electron emission coefficient, or to use solid solutions of these ( Patent Documents 1-2).
JP-A-52-63663 JP 2007-95436 A

  However, CaO, SrO, BaO, and the like are chemically unstable as compared with MgO, and easily react with moisture and carbon dioxide in the air to form hydroxides and carbonates. When such a compound is formed, the secondary electron emission coefficient decreases, and the expected low voltage cannot be obtained, or the aging time required for the voltage reduction becomes very long. There was a problem of disappearing.

  Degradation due to such chemical reactions can be avoided by controlling the atmosphere gas of work when producing a small amount at the laboratory level, but it is difficult to control the atmosphere of all processes at the manufacturing plant. And even if possible, it leads to higher costs. For this reason, even though the use of a material having a high secondary electron emission coefficient has been studied conventionally, only MgO has been put into practical use, and sufficient voltage reduction and high efficiency have been realized. It wasn't.

  The present invention is a PDP including a first panel and a second panel, wherein a discharge space is formed between the first panel and the second panel, wherein the first panel includes: , A substrate, a first electrode formed on the substrate, and a first dielectric layer covering the first electrode, and the second panel is formed on the substrate and the substrate. A second oxide layer, a second dielectric layer covering the second electrode, and a phosphor layer, wherein a metal oxide is disposed so as to face the discharge space, and the metal oxide Has a rock salt type crystal structure and is an oxide of at least one element selected from the group consisting of Ca, Sr and Ba, and at least selected from the group consisting of Mn, Fe, Co, Ni, Cu and Zn A PDP is provided which is a solid solution with an oxide of one element.

  Another aspect of the present invention is a method of manufacturing a PDP including a first panel and a second panel, wherein a discharge space is formed between the first panel and the second panel. And (i) a step of disposing a metal oxide on at least one panel selected from the group consisting of the first panel and the second panel; and (ii) the first panel and the second panel. Bonding the panel so that a discharge space is formed therein and the metal oxide faces the discharge space, and the first panel includes a substrate, and a substrate on the substrate. A first dielectric layer covering the first electrode, and the second panel includes a substrate, a second electrode formed on the substrate, A second dielectric layer covering the second electrode; and a phosphor layer; Is selected from the group consisting of oxides of at least one element selected from the group consisting of Ca, Sr and Ba and Mn, Fe, Co, Ni, Cu and Zn having a rock salt type crystal structure A method for producing a PDP that is a solid solution with an oxide of at least one element is provided.

  According to the present invention, a chemically stabilized metal oxide having a high secondary electron emission coefficient can be obtained, and a plasma display panel having a low driving voltage using the metal oxide can be provided.

  As a result of detailed studies, the inventors have investigated the fact that the crystal structure is changed to CaO, SrO, BaO having a rock salt type crystal structure, and the same divalent metal oxide, MnO, FeO, CoO, NiO. , CuO, ZnO can be dissolved in a solid solution to improve chemical stability. By using this as a secondary electron emission material, a PDP having a lower driving voltage than that obtained using MgO can be obtained. I found a thing.

  As alkaline earth metal oxides to be used, in addition to CaO, SrO, BaO, solid solutions of these, that is, (Ca, Sr) O, (Sr, Ba) O, (Ca, Ba) O, (Ca, Sr). Ba) O, or a solid solution of MgO, that is, (Ca, Mg) O, (Ca, Sr, Mg) O, or the like. The secondary electron emission coefficient of the alkaline earth metal oxide is higher in the order of BaO, SrO, and CaO (BaO is the highest). The chemical stability is higher in the order of CaO, SrO, and BaO (CaO is most stable). Also, it is easy to dissolve MnO, FeO, CoO, NiO, CuO and ZnO in an alkaline earth metal oxide in the order of CaO, SrO and BaO (CaO is the easiest). For this reason, from the aspect of improving the chemical stability of the metal oxide, as an oxide of at least one element selected from the group consisting of Ca, Sr and Ba, CaO, (Ca, Sr) O, (Ca, It is desirable to form the metal oxide by using an oxide containing Ca, such as Mg) O.

  Examples of a method for dissolving MnO, FeO, CoO, NiO, CuO, and ZnO in these include a solid phase method, a liquid phase method, and a gas phase method.

  In the solid-phase method, each metal oxide powder or raw material powder (metal hydroxide, metal carbonate, etc.) that becomes each metal oxide by heat treatment is mixed and heat-treated at a temperature of a certain level or more to react. Is the method. The advantage of this method is that a large amount of solid solution powder can be produced at low cost. According to the solid phase reaction method, a large amount of MnO can be dissolved in CaO.

  In addition, according to the solid phase reaction method, CoO, NiO and ZnO can usually be dissolved in about 10 mol% in CaO, and FeO and CuO can be dissolved in a smaller amount. Further, according to the solid phase reaction method, (Ca, Sr) O and (Sr, Ba) O can be synthesized at an arbitrary ratio. According to the solid-phase reaction method, (Ca, Mg) O can usually be synthesized if MgO is in the range of up to about 10 mol%, and if the addition amount of BaO is in a smaller range, (Ca , Ba) O can also be synthesized.

  The liquid phase method is a method in which a solution containing each metal is prepared and a solid phase is precipitated from the solution, or a solution is applied to a substrate, followed by drying, heat treatment, and the like to obtain a solid phase.

  The vapor phase method is a method for obtaining a film-like solid phase body by vapor deposition, sputtering, or the like. According to the gas phase method, it is possible to synthesize a desired composition in a wider range than the solid phase method by controlling the conditions.

  Next, regarding the amount of MnO, FeO, CoO, NiO, CuO, and ZnO to be dissolved in CaO, SrO, and BaO, the chemical stability becomes higher as the amount is increased. However, as described above, except for a combination of CaO and MnO, it is not always easy to make a large amount of solid solution. Moreover, when the amount of solid solution increases too much, it is also considered that a secondary electron emission coefficient falls. Further, MnO and the like are often more expensive than CaO and the like. From these points, it is better that the amount of solid solution is small. However, if the amount is too small, chemical stability is lowered.

  Since the required chemical stability varies depending on the actual manufacturing process conditions, it cannot be determined how much solid solution is good, but considering the above, Generally, it is 0.5 mol% or more and 50 mol% or less, more preferably 1.0 mol% or more and 30 mol% or less, and further preferably 2 mol% or more and 20 mol% or less.

  Next, as to which of MnO, FeO, CoO, NiO, CuO, and ZnO should be selected, MnO should be dissolved in CaO, SrO, BaO, etc., compared to FeO, CoO, NiO, CuO, and ZnO. Is easy. In addition, by dissolving MnO in solid solution, the amount of metal oxides (eg ZnO, MgO, etc.) that are relatively difficult to dissolve in CaO, SrO, BaO, etc. is increased in CaO, SrO, BaO, etc. Can be made.

  CoO, ZnO, and NiO have a stronger effect of increasing chemical stability in metal oxides than MnO, FeO, and CuO. CoO and ZnO have a stronger effect than NiO. Although CoO is not comparable to MnO, it can be easily dissolved in CaO, SrO, BaO and the like as compared with FeO, NiO, CuO and ZnO. ZnO can be easily dissolved in CaO, SrO, BaO and the like in a state where coloring is avoided.

  Considering the above comprehensively, ZnO and MnO are the most desirable, followed by CoO and NiO, but an appropriate material may be used depending on the application. Moreover, these may be made into solid solution each independently, and may be made into solid solution combining 2 or more types.

  Next, as to which part of the PDP panel these solid solutions are to be formed, generally, they may be formed on a dielectric layer covering the electrodes on the front plate. However, even if it is formed on another part, for example, on the phosphor or on the rib surface, it may be located on the discharge space. That is, it should just be formed on at least one panel selected from the front plate and the back plate.

  As a result, the effect of lowering the driving voltage is recognized to some extent as compared with those not forming these solid solutions.

  Next, these solid solutions may be arranged in at least one form selected from particles and a film.

  For example, considering the case of forming on the dielectric layer covering the electrodes on the front plate, these solid solution films may be formed on the dielectric layer instead of the MgO film normally formed as a protective film. Further, these solid solution powders may be dispersed on the dielectric layer. Alternatively, an MgO film may be formed on the dielectric layer, and a film of these solid solutions may be further formed, or a powder of these solid solutions may be dispersed. What is necessary is just to select the particle diameter in the case of using by powder according to cell size etc. within the range of about 0.1 micrometer-10 micrometers.

  Note that in this specification, oxides of Mn, Fe, Co, Ni, Cu, and Zn are described as MnO, FeO, CoO, NiO, CuO, and ZnO for convenience, but this is not necessarily the case for these metal elements. The valence is not specified to be bivalent, but may be a metal oxide solid solution having a rock salt type crystal structure as a final form. Moreover, even if a metal element other than the above is contained in the solid solution phase, it does not matter as long as it does not impair the stability and does not break the crystal structure.

  Next, a specific example of the PDP of the present invention will be described with reference to the drawings. An example of a PDP according to the present invention is shown in FIGS. FIG. 1 is an exploded perspective view of the PDP 100. FIG. 2 is a longitudinal sectional view of the PDP 100 (a sectional view taken along line I-I in FIG. 1). As shown in FIGS. 1 and 2, the PDP 100 has a front panel 1 and a back panel 8. A discharge space 14 is formed between the front panel 1 and the back panel 8. This PDP is an AC surface discharge type, and has the same configuration as that of the conventional PDP except that the protective layer is formed of the above-described metal oxide solid solution.

  The front plate 1 is formed so as to cover the front glass substrate 2, the display electrode 5 composed of the transparent conductive film 3 and the bus electrode 4 formed on the inner side surface (the surface facing the discharge space 14), and the display electrode 5. A dielectric layer 6 and a protective layer 7 formed on the dielectric layer 6. The display electrode 5 is formed by laminating a bus electrode 4 made of Ag or the like on a transparent conductive film 3 made of ITO or tin oxide in order to ensure good conductivity.

  The back plate 8 includes a back glass substrate 9, an address electrode 10 formed on one side thereof, a dielectric layer 11 formed so as to cover the address electrode 10, and a partition wall 12 provided on the top surface of the dielectric layer 11. And a phosphor layer formed between the barrier ribs 12. The phosphor layer is formed so that the red phosphor layer 13 (R), the green phosphor layer 13 (G), and the blue phosphor layer 13 (B) are arranged in this order.

As the phosphor constituting the phosphor layer, for example, BaMgAl ₁₀ O ₁₇ : Eu is used as a blue phosphor, Zn ₂ SiO ₄ : Mn is used as a green phosphor, and Y ₂ O ₃ : Eu is used as a red phosphor. it can.

  The front plate 1 and the back plate 8 are arranged so that the longitudinal directions of the display electrodes 5 and the address electrodes 10 are orthogonal to each other and face each other, and are joined using a sealing member (not shown).

  The discharge space 14 is filled with a discharge gas composed of a rare gas component such as He, Xe, or Ne.

  The display electrode 5 and the address electrode 10 are each connected to an external drive circuit (not shown), and a discharge is generated in the discharge space 14 by a voltage applied from the drive circuit, and a short wavelength (wavelength generated by the discharge). The phosphor layer 13 is excited by ultraviolet rays of 147 nm and emits visible light. The metal oxide solid solution described above is used for the protective layer 7.

  Another example of a PDP according to the present invention is shown in FIGS. FIG. 3 is an exploded perspective view of the PDP 200. FIG. 4 is a longitudinal sectional view of the PDP 200 (a sectional view taken along the line II in FIG. 3). The PDP 200 has the same structure as the PDP 100 except that the protective layer 7 is made of MgO and the metal oxide 20 is arranged in the form of particles on the protective layer 7. Also in the PDP 200, the metal oxide 20 faces the discharge space 14.

  Next, a method for manufacturing a PDP panel in the case where a conventional MgO film is used as the protective layer 7 and the above-described metal oxide solid solution powder is dispersed thereon will be described with an example. First, a front plate is produced. A plurality of line-shaped transparent electrodes are formed on one main surface of the flat front glass substrate. Subsequently, after the silver paste is applied on the transparent electrode, the entire front glass substrate is heated, thereby baking the silver paste and forming the display electrode.

  A glass paste containing the dielectric layer glass in the PDP of the present invention is applied to the main surface of the front glass substrate by a blade coater method so as to cover the display electrodes. Thereafter, the entire front glass substrate is held at 90 ° C. for 30 minutes to dry the glass paste, and then baked at a temperature of about 580 ° C. for 10 minutes.

  Magnesium oxide (MgO) is deposited on the dielectric layer by an electron beam evaporation method and baked to form a protective layer. The firing temperature at this time is around 500 ° C.

  On the MgO layer, a liquid in which a powdered metal oxide solid solution is dispersed in an organic solvent such as ethanol is sprayed and dried to form a sprayed film.

  Next, a back plate is produced. After applying a plurality of silver pastes in a line on one main surface of a flat back glass substrate, the entire back glass substrate is heated and the silver paste is baked to form address electrodes.

  A partition wall is formed by applying a glass paste between adjacent address electrodes and firing the glass paste by heating the entire back glass substrate.

  By applying phosphor inks of R, G, and B colors between adjacent barrier ribs, and heating the back glass substrate to about 500 ° C. and baking the phosphor ink, a resin component in the phosphor ink (Binder) and the like are removed to form a phosphor layer.

  The front plate and the back plate thus obtained are bonded using a sealing glass. The temperature at this time is around 500 ° C. Thereafter, after the sealed interior is evacuated to high vacuum, a rare gas is sealed. A PDP is obtained as described above.

  Note that the above-described PDP and its manufacturing method are merely examples, and the present invention is not limited thereto.

  When the metal oxide solid solution is formed as a thin film instead of the MgO protective layer, a normal thin film process such as electron beam evaporation may be used as appropriate, similarly to MgO. On the other hand, when the metal oxide solid solution powder is dispersed, the powder is dispersed and dispersed as described above, a spin coater or the like is used, or a printing method or the like may be appropriately used.

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

[Metal oxide solid solution]
In this example, the improvement effect of chemical stability is shown when MnO, FeO, CoO, NiO, CuO, and ZnO are dissolved in CaO by the solid phase powder method.

As starting materials, reagent-grade CaCO ₃ , MnCO ₃ , FeO, CoO _1.33 , NiO, CuO, ZnO and MgO were used. These raw materials were weighed so that the molar ratio of each metal ion was as shown in Table 1, wet-mixed using a ball mill, and then dried to obtain a mixed powder.

  This mixed powder was put in a platinum crucible, and in an electric furnace, those using Mn and Fe were baked in nitrogen and the others in air at 1500 ° C. for 4 hours. The obtained powder was dry-pulverized to an average particle size of 2 μm using a ball mill. A part of the pulverized powder was analyzed using an X-ray diffraction method, and the lattice constant was measured from the diffraction peak of the CaO phase. Except for the sample 1, although the degree varies depending on the amount and type of the metal oxide to be combined, all have a small lattice constant, and at least a part of MnO, FeO, CoO, NiO, CuO, ZnO is at least partially CaO. It was confirmed that it was dissolved in No. 1 was CaO. However, in addition to the solid solution phase mainly composed of CaO, some other phases are generated. This means that the sample contains crystal components (for example, CoO and MgO) that are not dissolved in CaO. Table 1 shows an example in which a plurality of types of phases are detected by the X-ray diffraction method as “double phase” and an example in which only a single type of phase is detected as “single phase”.

  Next, a portion of the pulverized powder was weighed and then filled into a porous cell having no hygroscopicity. This cell was placed in a constant temperature and humidity chamber in 40 ° C. and 70% air and left for 10 hours. The weight increase rate was measured. A lower weight increase rate means that the pulverized powder is an oxide having excellent chemical stability. Furthermore, a part of the powder after the treatment was analyzed by using an X-ray diffraction method, and a product phase was identified. The weight increase rate of each pulverized powder is shown in Table 1.

No. in Table 1 From 1, it was found that the weight increase was very large with CaO alone. No. In the X-ray diffraction after the constant temperature and humidity treatment of the sample No. 1, Ca (OH) ₂ and CaCO ₃ were the main phases, and only part of CaO remained.

  On the other hand, No. in which Mn, Fe, Co, Ni, Cu and Zn were dissolved. In 2 to 7, the weight increase rate decreased to some extent, and the chemical stability was improved. However, even when the same divalent metal is used, No. 1 in which Mg is dissolved is used. In No. 8, the weight increase rate hardly changed, and the chemical stability improving effect was not observed.

  Next, no. 9 to 23 show the results of increasing the blending ratio for Mn, Co, Ni, Zn, and Mg. Depending on the type of metal element, the composition range that becomes a single phase under the present synthesis conditions is different, but with respect to Mn, Co, Ni, and Zn, as the compounding ratio increases, the weight increases within the range that is a single phase. It was clear that the chemical stability was improved by steadily decreasing and solid solution.

  On the other hand, with Mg, even if the blending ratio was increased, the further solid solution hardly progressed, and the effect of improving the weight increase was hardly recognized. However, no. As shown in 24, when combined with other elements, solid solution progressed, and the effect of reducing weight gain was also observed. Therefore, adding MgO was effective.

[PDP]
In this example, a PDP using a metal oxide solid solution with improved chemical stability according to the present invention is shown. A front glass substrate made of flat soda lime glass having a thickness of about 2.8 mm was prepared. On the surface of the front glass substrate, an ITO (transparent electrode) material was applied in a predetermined pattern and dried. Next, a plurality of silver pastes, which are a mixture of silver powder and an organic vehicle, were applied in a line shape, and then the front glass substrate was heated, whereby the silver paste was baked to form display electrodes.

  A glass paste is applied to the front panel on which the display electrode is manufactured by using a blade coater method, and the glass paste is dried by holding at 90 ° C. for 30 minutes, and then baked at a temperature of 585 ° C. for 10 minutes. A 30 μm dielectric layer was formed.

  Magnesium oxide (MgO) was deposited on the dielectric layer by an electron beam deposition method, and then baked at 500 ° C. to form a protective layer.

  Next, no. The powders 1 and 18 were dispersed in ethanol, sprayed thinly on the MgO layer by a spray method, and dried at 90 ° C. At this time, the coating ratio was set to about 10% by adjusting the concentration. For comparison, a sample that was not sprayed and a sample that was sprayed with MgO powder were also prepared.

  On the other hand, a back plate was produced by the following method. First, an address electrode mainly composed of silver was formed in a stripe shape on a rear glass substrate made of soda lime glass by screen printing, and then a dielectric layer having a thickness of about 8 μm was formed in the same manner as the front plate. .

  Next, partition walls were formed on the dielectric layer using glass paste between adjacent address electrodes. The partition was formed by repeating screen printing and baking.

  Subsequently, the phosphor layer of red (R), green (G), and blue (B) is applied to the surface of the dielectric layer exposed between the wall surfaces of the barrier ribs and the barrier ribs, and then dried and fired to phosphor layer Was made.

  The produced front plate and back plate were bonded at 500 ° C. using sealing glass. And after exhausting the inside of discharge space, Xe was enclosed as discharge gas, and PDP was produced.

  When the produced panel was connected to a drive circuit to emit light, the drive voltage was reduced by 9% when MgO powder was dispersed as compared with the case of using only the MgO thin film. When 1 powder was sprayed, no voltage drop was observed. On the other hand, no. When 18 powders were sprayed, it decreased by 16%, and the improvement effect could be confirmed.

  The present invention can provide a plasma display panel having improved discharge characteristics and a method of manufacturing the same.

It is a disassembled perspective view for demonstrating an example of PDP by this invention. It is a longitudinal cross-sectional view of PDP shown in FIG. It is a disassembled perspective view for demonstrating other examples of PDP by this invention. It is a longitudinal cross-sectional view of PDP shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front plate 2 Front glass substrate 3 Transparent conductive film 4 Bus electrode 5 Display electrode 6 Dielectric layer 7 Protective layer 8 Back plate 9 Back glass substrate 10 Address electrode 11 Dielectric layer 12 Partition 13 Phosphor layer 14 Discharge space 20 Metal oxide object

Claims (10)

A plasma display panel comprising a first panel and a second panel, wherein a discharge space is formed between the first panel and the second panel,
The first panel includes a substrate, a first electrode formed on the substrate, and a first dielectric layer covering the first electrode,
The second panel includes a substrate, a second electrode formed on the substrate, a second dielectric layer covering the second electrode, and a phosphor layer,
A metal oxide is disposed so as to face the discharge space,
The metal oxide has a rock salt type crystal structure, and an oxide of at least one element selected from the group consisting of Ca, Sr and Ba, and a group consisting of Mn, Fe, Co, Ni, Cu and Zn A plasma display panel, which is a solid solution with an oxide of at least one element selected from the above.   The plasma display panel according to claim 1, wherein the metal oxide contains Ca.   The plasma display panel according to claim 1, wherein the metal oxide further contains Mg.   The plasma display panel according to claim 1, wherein the metal oxide is arranged in at least one form selected from particles and a film.   The plasma display panel according to claim 1, wherein the metal oxide is formed on at least one panel selected from the first panel and the second panel.   The plasma display panel according to claim 1, wherein a protective layer is formed on the first dielectric layer.   The plasma display panel according to claim 6, wherein the protective layer is made of MgO.   The plasma display panel according to claim 6 or 7, wherein the metal oxide is disposed on the protective layer in at least one form selected from particles and a film.   The plasma display panel according to claim 6, wherein the protective layer includes the metal oxide. A method for manufacturing a plasma display panel, comprising a first panel and a second panel, wherein a discharge space is formed between the first panel and the second panel,
(I) disposing a metal oxide on at least one panel selected from the group consisting of the first panel and the second panel;
(Ii) bonding the first panel and the second panel so that a discharge space is formed therein and the metal oxide faces the discharge space;
The first panel includes a substrate, a first electrode formed on the substrate, and a first dielectric layer covering the first electrode,
The second panel includes a substrate, a second electrode formed on the substrate, a second dielectric layer covering the second electrode, and a phosphor layer,
The metal oxide has a rock salt type crystal structure, and includes an oxide of at least one element selected from the group consisting of Ca, Sr, and Ba, and Mn, Fe, Co, Ni, Cu, and Zn. A method for producing a plasma display panel, which is a solid solution with an oxide of at least one element selected from the group consisting of:

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