JP2013037798A - Plasma display panel and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma display panel that has high-definition and high-luminance display performance and is low in power consumption.SOLUTION: A plasma display panel comprises: a front plate that has display electrode pairs, a dielectric layer, and a protective layer; and a rear plate that is arranged opposite the front plate with a discharge space formed therebetween. The protective layer includes, at least, a first metal oxide and a second metal oxide. The first metal oxide is magnesium oxide, and the second metal oxide is any one of calcium oxide, strontium oxide and barium oxide. The second metal oxide has a higher concentration on a side of the protective layer facing the discharge space than in the middle of the protective layer.

Description

  The technology disclosed herein relates to a plasma display panel used for a display device or the like and a manufacturing method thereof.

  A plasma display panel (hereinafter referred to as PDP) includes a front plate and a back plate. The front plate includes a glass substrate, a display electrode formed on one main surface of the glass substrate, a dielectric layer that covers the display electrode and functions as a capacitor, and magnesium oxide formed on the dielectric layer It is comprised with the protective layer which consists of (MgO).

  In order to increase the number of initial electron emissions from the protective layer, for example, attempts have been made to add silicon (Si) or aluminum (Al) to MgO of the protective layer (for example, see Patent Document 1).

JP 2002-260535 A

  In order to reduce the power consumption of the PDP, it is required to keep the discharge voltage required for image display low. The present invention achieves this object and provides a PDP that can be driven at a low voltage.

  In the PDP of the present invention, a front plate having a display electrode pair, a dielectric layer, and a protective layer, and a rear plate are disposed to face each other in a discharge space, and the protective layer includes at least a first metal oxide. And the second metal oxide, the first metal oxide is magnesium oxide, and the second metal oxide is one of calcium oxide, strontium oxide, and barium oxide, and the protection The second metal oxide concentration on the discharge space side of the layer is higher than the concentration in the protective layer.

  The PDP manufacturing method of the present invention is a PDP manufacturing method in which a front plate and a back plate having a protective layer are formed in a discharge space so as to face each other and sealed, and the discharge space is exhausted. The protective layer includes at least a first metal oxide and a second metal oxide, the first metal oxide is magnesium oxide, and the second metal oxide is calcium oxide, One of strontium oxide and barium oxide, and the concentration of the second metal oxide on the discharge space side of the protective layer is higher than the concentration in the protective layer, and after the formation of the protective layer, the surface of the protective layer It is characterized by exposing to reducing organic gas.

  According to the present invention, a PDP that can be driven at a low voltage can be provided, which can contribute to a reduction in power consumption of the PDP.

The perspective view which shows the structure of PDP concerning embodiment Sectional drawing which shows the structure of the front plate concerning embodiment The figure which shows the manufacturing flow of PDP concerning an embodiment The figure which shows the 1st temperature profile example The figure which shows the 2nd temperature profile example The figure which shows the 3rd temperature profile example The figure which shows the X-ray-diffraction analysis result of the base layer surface concerning embodiment The figure which shows the X-ray-diffraction analysis result of the other underlayer surface concerning embodiment Enlarged view of aggregated particles according to the embodiment The figure which shows the change of the calcium concentration of a PDP underlayer The figure which shows the change of the calcium concentration of PDP underlayer thickness direction

[1. Structure of PDP1]
The basic structure of the PDP is a general AC surface discharge type PDP. As shown in FIGS. 1 and 2, the PDP 1 has a front plate 2 made of a front glass substrate 3 and a back plate 10 made of a back glass substrate 11 and the like facing each other. The front plate 2 and the back plate 10 are hermetically sealed with a sealing material whose outer peripheral portion is made of glass frit or the like. The discharge space 16 inside the sealed PDP 1 is filled with discharge gas such as neon (Ne) and xenon (Xe) at a pressure of 53 kPa (400 Torr) to 80 kPa (600 Torr).

  On the front glass substrate 3, a pair of strip-like display electrodes 6 each composed of the scanning electrodes 4 and the sustain electrodes 5 and a plurality of black stripes 7 are arranged in parallel to each other. A dielectric layer 8 that functions as a capacitor is formed on the front glass substrate 3 so as to cover the display electrodes 6 and the black stripes 7. Further, a protective layer 9 made of magnesium oxide (MgO) or the like is formed on the surface of the dielectric layer 8. The protective layer 9 will be described later in detail.

Scan electrode 4 and sustain electrode 5 are each formed by laminating a bus electrode made of Ag on a transparent electrode made of a conductive metal oxide such as indium tin oxide (ITO), tin oxide (SnO ₂ ), and zinc oxide (ZnO). Has been.

  On the rear glass substrate 11, a plurality of data electrodes 12 made of a conductive material mainly composed of silver (Ag) are arranged in parallel to each other in a direction orthogonal to the display electrodes 6. The data electrode 12 is covered with a base dielectric layer 13. Further, a partition wall 14 having a predetermined height is formed on the underlying dielectric layer 13 between the data electrodes 12 to divide the discharge space 16. In the grooves between the barrier ribs 14, a phosphor layer 15 that emits red light by ultraviolet rays, a phosphor layer 15 that emits green light, and a phosphor layer 15 that emits blue light are sequentially applied and formed for each data electrode 12. Yes. A discharge cell is formed at a position where the display electrode 6 and the data electrode 12 intersect. Discharge cells having red, green, and blue phosphor layers 15 arranged in the direction of the display electrode 6 serve as pixels for color display.

  In the present embodiment, the discharge gas sealed in the discharge space 16 contains 10% by volume to 30% by volume of Xe.

[2. Manufacturing method of PDP1]
As shown in FIG. 3, the manufacturing method of the PDP 1 according to this embodiment includes a front plate manufacturing step A1, a back plate manufacturing step B1, a frit coating step B2, a sealing step C1, a reducing gas introduction step C2, and an exhaust step. C3 and discharge gas supply step C4.

[2-1. Front plate manufacturing process A1]
In front plate manufacturing step A1, scan electrodes 4, sustain electrodes 5, and black stripes 7 are formed on front glass substrate 3 by photolithography. Scan electrode 4 and sustain electrode 5 have metal bus electrodes 4b and 5b containing silver (Ag) for ensuring conductivity. Scan electrode 4 and sustain electrode 5 have transparent electrodes 4a and 5a. The metal bus electrode 4b is laminated on the transparent electrode 4a. The metal bus electrode 5b is laminated on the transparent electrode 5a.

  For the material of the transparent electrodes 4a and 5a, indium tin oxide (ITO) or the like is used to ensure transparency and electrical conductivity. First, an ITO thin film is formed on the front glass substrate 3 by sputtering or the like. Next, transparent electrodes 4a and 5a having a predetermined pattern are formed by lithography.

  As a material for the metal bus electrodes 4b and 5b, an electrode paste containing silver (Ag), a glass frit for binding silver, a photosensitive resin, a solvent, and the like is used. First, an electrode paste is applied on the front glass substrate 3 by a screen printing method or the like. Next, the solvent in the electrode paste is removed by a drying furnace. Next, the electrode paste is exposed through a photomask having a predetermined pattern.

  Next, the electrode paste is developed to form a metal bus electrode pattern. Finally, the metal bus electrode pattern is fired at a predetermined temperature in a firing furnace. That is, the photosensitive resin in the metal bus electrode pattern is removed. Further, the glass frit in the metal bus electrode pattern is melted. The molten glass frit is vitrified again after firing. Metal bus electrodes 4b and 5b are formed by the above steps. The black stripe 7 is formed of a material containing a black pigment.

  Next, the dielectric layer 8 is formed. As a material for the dielectric layer 8, a dielectric paste containing a dielectric glass frit, a resin, a solvent, and the like is used. First, a dielectric paste is applied on the front glass substrate 3 so as to cover the display electrode 6 with a predetermined thickness by a die coating method or the like. Next, the solvent in the dielectric paste is removed by a drying furnace. Finally, the dielectric paste is fired at a predetermined temperature in a firing furnace. That is, the resin in the dielectric paste is removed. In addition, the dielectric glass frit melts and resolidifies. Through the above steps, the dielectric layer 8 is formed. Here, besides the method of die coating the dielectric paste, a screen printing method, a spin coating method, or the like can be used.

  Then, the protective layer 9 is formed. Details of the protective layer 9 will be described later.

  The front plate 2 having predetermined components on the front glass substrate 3 is completed through the above steps.

[2-2. Back plate manufacturing process B1]
Data electrodes 12 are formed on the rear glass substrate 11 by photolithography. As a material of the data electrode 12, a data electrode paste containing silver (Ag) for ensuring conductivity, a glass frit for binding silver, a photosensitive resin, a solvent, and the like is used. First, the data electrode paste is applied on the rear glass substrate 11 with a predetermined thickness by a screen printing method or the like. Next, the solvent in the data electrode paste is removed by a drying furnace. Next, the data electrode paste is exposed through a photomask having a predetermined pattern. Next, the data electrode paste is developed to form a data electrode pattern. Finally, the data electrode pattern is fired at a predetermined temperature in a firing furnace. That is, the photosensitive resin in the data electrode pattern is removed. Further, the glass frit in the data electrode pattern is melted. The molten glass frit is vitrified again after firing. The data electrode 12 is formed by the above process. Here, besides the method of screen printing the data electrode paste, a sputtering method, a vapor deposition method, or the like can be used.

  Next, the base dielectric layer 13 is formed. As a material for the base dielectric layer 13, a base dielectric paste containing a dielectric glass frit, a resin, a solvent, and the like is used. First, a base dielectric paste is applied by a screen printing method or the like so as to cover the data electrode 12 on the rear glass substrate 11 on which the data electrode 12 is formed with a predetermined thickness. Next, the solvent in the base dielectric paste is removed by a drying furnace. Finally, the base dielectric paste is fired at a predetermined temperature in a firing furnace. That is, the resin in the base dielectric paste is removed. Further, the dielectric glass frit is melted. The molten dielectric glass frit is vitrified again after firing. Through the above steps, the base dielectric layer 13 is formed. Here, other than the method of screen printing the base dielectric paste, a die coating method, a spin coating method, or the like can be used. Further, a film to be the base dielectric layer 13 can be formed by CVD (Chemical Vapor Deposition) method or the like without using the base dielectric paste.

  Next, the partition wall 14 is formed by photolithography. As a material for the partition wall 14, a partition paste containing a filler, a glass frit for binding the filler, a photosensitive resin, a solvent, and the like is used. First, the barrier rib paste is applied on the underlying dielectric layer 13 with a predetermined thickness by a die coating method or the like. Next, the solvent in the partition wall paste is removed by a drying furnace. Next, the barrier rib paste is exposed through a photomask having a predetermined pattern. Next, the barrier rib paste is developed to form a barrier rib pattern. Finally, the partition pattern is fired at a predetermined temperature in a firing furnace. That is, the photosensitive resin in the partition pattern is removed. Further, the glass frit in the partition wall pattern is melted. The molten glass frit is vitrified again after firing. The partition wall 14 is formed by the above process. Here, in addition to the photolithography method, a sandblast method or the like can be used.

  Next, the phosphor layer 15 is formed. As the material of the phosphor layer 15, a phosphor paste containing phosphor particles, a binder, a solvent, and the like is used. First, a phosphor paste is applied on the base dielectric layer 13 between adjacent barrier ribs 14 and on the side surfaces of the barrier ribs 14 by a dispensing method or the like. Next, the solvent in the phosphor paste is removed by a drying furnace. Finally, the phosphor paste is fired at a predetermined temperature in a firing furnace. That is, the resin in the phosphor paste is removed. The phosphor layer 15 is formed by the above steps. Here, in addition to the dispensing method, a screen printing method or the like can be used.

  Through the above steps, the back plate 10 having predetermined components on the back glass substrate 11 is completed.

[2-3. Frit application process B2]
A glass frit which is a sealing member is applied outside the image display area of the back plate 10 manufactured by the back plate manufacturing step B1. Thereafter, the glass frit is temporarily fired at a temperature of about 350 ° C. A solvent component etc. are removed by temporary baking.

As the sealing member, a frit containing bismuth oxide or vanadium oxide as a main component is desirable. Examples of the frit containing bismuth oxide as a main component include, for example, a Bi ₂ O ₃ —B ₂ O ₃ —RO—MO system (where R is any one of Ba, Sr, Ca, and Mg, and M is Any of Cu, Sb, and Fe)) and a filler made of an oxide such as Al ₂ O ₃ , SiO ₂ , and cordierite can be used. In addition, as a frit containing vanadium oxide as a main component, for example, a filler made of an oxide such as Al ₂ O ₃ , SiO ₂ , cordierite is added to a V ₂ O ₅ —BaO—TeO—WO glass material. Things can be used.

[2-4. From sealing process C1 to discharge gas supply process C4]
The front plate 2 and the back plate 10 that has undergone the frit coating step B2 are arranged to face each other, and the peripheral portion is sealed by a sealing member. Thereafter, a discharge gas is sealed in the discharge space 16.

  The sealing process C1, the reducing gas introduction process C2, the exhaust process C3, and the discharge gas supply process C4 according to the present embodiment perform the processing of the temperature profile illustrated in FIGS. 4 to 6 in the same apparatus. .

  The sealing temperature in FIGS. 4 to 6 is a temperature at which the front plate 2 and the back plate 10 are sealed by a frit that is a sealing member. The sealing temperature in the present embodiment is about 490 ° C., for example. The softening point in FIGS. 4 to 6 is the temperature at which the frit as the sealing member softens. The softening point in the present embodiment is about 430 ° C., for example. Furthermore, the exhaust temperature in FIGS. 4 to 6 is a temperature at which a gas containing a reducing organic gas is exhausted from the discharge space. The exhaust temperature in the present embodiment is about 400 ° C., for example.

[2-4-1. First temperature profile]
As shown in FIG. 4, first, in the sealing step C1, the temperature rises from room temperature to the sealing temperature. The temperature is then maintained at the sealing temperature for the period ab. Thereafter, the temperature drops from the sealing temperature to the exhaust temperature during the period bc. In the period bc, the inside of the discharge space is exhausted. That is, the discharge space is in a reduced pressure state.

  Next, in the reducing gas introduction step C2, the temperature is maintained at the exhaust temperature for the period cd. A gas containing a reducing organic gas is introduced into the discharge space during the period cd. The protective layer 9 is exposed to a gas containing a reducing organic gas during the period cd.

  Thereafter, in the exhaust process C3, the temperature is maintained at the exhaust temperature for a predetermined period. Thereafter, the temperature drops to about room temperature. In the period d-e, the gas containing the reducing organic gas is discharged by exhausting the inside of the discharge space.

  Next, in the discharge gas supply process C4, a discharge gas is introduced into the discharge space. That is, the discharge gas is introduced in a period after e when the temperature drops to about room temperature.

[2-4-2. Second temperature profile]
As shown in FIG. 5, first, in the sealing step C1, the temperature rises from room temperature to the sealing temperature. The temperature is then maintained at the sealing temperature for the period ab. Thereafter, the temperature falls from the sealing temperature to the exhaust temperature during the period bc. The discharge space is exhausted during the period cd1 where the temperature is maintained at the exhaust temperature. That is, the discharge space is in a reduced pressure state.

  Next, in the reducing gas introduction step C2, the temperature is maintained at the exhaust temperature during the period d1-d2. A gas containing a reducing organic gas is introduced into the discharge space during the period d1-d2. During the period d1-d2, the protective layer 9 is exposed to a gas containing a reducing organic gas.

  Thereafter, in the exhaust process C3, the temperature is maintained at the exhaust temperature for a predetermined period. Thereafter, the temperature drops to about room temperature. During the period d2-e, the discharge space is exhausted, whereby a gas containing a reducing organic gas is exhausted.

  Next, in the discharge gas supply process C4, a discharge gas is introduced into the discharge space. That is, the discharge gas is introduced in a period after e when the temperature drops to about room temperature.

[2-4-3. Third temperature profile]
As shown in FIG. 6, first, in the sealing step C1, the temperature rises from room temperature to the sealing temperature. Next, the temperature is maintained at the sealing temperature for the period ab1-b2. The discharge space is exhausted during the period ab1. That is, the discharge space is in a reduced pressure state. Thereafter, the temperature falls from the sealing temperature to the exhaust temperature during the period b2-c.

  The reducing gas introduction process C2 is performed within the period of the sealing process C1. The temperature is maintained at the sealing temperature for the period b1-b2. Thereafter, the temperature falls to the exhaust temperature during the period b2-c. A gas containing a reducing organic gas is introduced into the discharge space during the period of b1-b2. During the period of b1-b2, the protective layer 9 is exposed to a gas containing a reducing organic gas.

  Thereafter, in the exhaust process C3, the temperature is maintained at the exhaust temperature for a predetermined period. Thereafter, the temperature drops to about room temperature. During the period ce, the gas containing the reducing organic gas is discharged by exhausting the discharge space.

  Next, in the discharge gas supply process C4, a discharge gas is introduced into the discharge space. That is, the discharge gas is introduced in a period after e when the temperature drops to about room temperature.

  In addition, it has an almost equivalent effect in any temperature profile.

[2-4-4. Details of reducing organic gas]
As shown in Table 1, the reducing organic gas is preferably a CH-based organic gas having a molecular weight of 58 or less and a large reducing power. When at least one selected from various reducing organic gases is mixed with a rare gas or nitrogen gas, a gas containing the reducing organic gas is produced.

  In Table 1, column C means the number of carbon atoms contained in one molecule of organic gas. The column of H means the number of hydrogen atoms contained in one molecule of the organic gas.

  As shown in Table 1, “A” is given to a gas having a vapor pressure of 100 kPa or higher at 0 ° C. in the vapor pressure column. Furthermore, “C” is given to the gas whose vapor pressure at 0 ° C. is smaller than 100 kPa. In the boiling point column, a gas having a boiling point of 0 ° C. or less at 1 atm is marked with “A”. Furthermore, “C” is attached to a gas having a boiling point of greater than 0 ° C. at 1 atmosphere. In the column for easy decomposition, “A” is given to the gas that is easily decomposed. “B” is attached to a gas that is easily decomposed. In the column of reducing power, “A” is given to the gas having sufficient reducing power.

  In Table 1, “A” means good characteristics. “B” means normal characteristics. “C” means insufficient properties.

  From the viewpoint of easy handling of organic gas in the manufacturing process of PDP, a reducing organic gas that can be supplied in a gas cylinder is desirable. Also, considering the ease of handling in the manufacturing process of PDP, a reducing organic gas having a vapor pressure at 100 ° C. of 100 kPa or higher, a reducing organic gas having a boiling point of 0 ° C. or lower, or a reducing organic gas having a low molecular weight is present. desirable.

  Furthermore, part of the gas containing the reducing organic gas may remain in the discharge space even after the exhaust process C3. Therefore, it is desirable that the reducing organic gas has a characteristic that it is easily decomposed.

  Reducing organic gas is a carbon that does not contain oxygen selected from acetylene, ethylene, methylacetylene, propadiene, propylene and cyclopropane, taking into consideration the ease of handling in the manufacturing process and the property of being easily decomposed. Hydrogen gas is desirable.

  At least one selected from these reducing organic gases may be mixed with a rare gas or nitrogen gas. The lower limit of the mixing ratio of the rare gas or nitrogen gas and the reducing organic gas is determined according to the combustion ratio of the reducing organic gas to be used. The upper limit is about several volume%. If the mixing ratio of the reducing organic gas is too high, the organic component is likely to be polymerized to become a polymer. In this case, the polymer remains in the discharge space and affects the characteristics of the PDP. Therefore, it is preferable to appropriately adjust the mixing ratio according to the component of the reducing organic gas to be used.

  The inventors conducted a similar study using hydrogen gas as another example of the reducing gas, but did not achieve the same effect as the reducing organic gas.

  Note that MgO, CaO, SrO, BaO, and the like are highly reactive with impurity gases such as water, carbon dioxide, and hydrocarbons. In particular, by reacting with water and carbon dioxide, the discharge characteristics are likely to deteriorate, and the discharge characteristics of each discharge cell are likely to vary.

  Therefore, in the sealing step C1, it is preferable to flow an inert gas so that the inside of the discharge space 16 is in a positive pressure state through a through-hole opened in the discharge space 16, and then perform sealing. This is because the reaction between the underlayer 91 and the impurity gas can be suppressed. Nitrogen, helium, neon, argon, xenon, etc. can be used as the inert gas.

  Moreover, you may flow dry air (dry gas) instead of an inert gas. This is because at least the reaction with water can be suppressed and the production cost can be reduced compared with the inert gas.

  Specifically, in the sealing step C1 shown in FIGS. 4 to 6, for example, nitrogen gas may be flowed at a flow rate of about 2 L / min during a period until x when the temperature reaches the softening point. The discharge space 16 is maintained at a positive pressure by nitrogen gas. When the temperature exceeds the softening point, the supply of nitrogen gas is stopped. The discharge space 16 is kept at a positive pressure by nitrogen gas. The temperature is maintained at the sealing temperature for the period ab. The discharge space 16 is filled with nitrogen gas. Thereafter, the temperature drops from the sealing temperature to the exhaust temperature during the period bc. During the period bc, the nitrogen gas that has filled the discharge space 16 is exhausted. That is, the discharge space is in a reduced pressure state. The description for the subsequent period is the same as the above description.

[3. Details of Protective Layer 9]
The protective layer 9 is required to have a function of holding electric charge for generating discharge and a function of emitting secondary electrons during sustain discharge. The applied voltage is reduced by improving the charge retention performance. As the number of secondary electron emission increases, the sustain discharge voltage is reduced.

[3-1. Underlayer 91]
The protective layer 9 according to the present embodiment includes a base layer 91 and aggregated particles 92. The underlayer 91 includes at least a first metal oxide and a second metal oxide. The first metal oxide is MgO, and the second metal oxide is one selected from the group consisting of CaO, SrO and BaO. Furthermore, the underlayer 91 has at least one peak in the X-ray diffraction analysis. This peak is between the first peak in the X-ray diffraction analysis of the first metal oxide and the second peak in the X-ray diffraction analysis of the second metal oxide. The first peak and the second peak have the same plane orientation as the plane orientation indicated by the peak of the underlayer 91.

  In FIG. 7, the horizontal axis represents the Bragg diffraction angle (2θ). The vertical axis represents the intensity of the X-ray diffraction wave. The unit of the diffraction angle is expressed in degrees where one round is 360 degrees. The intensity of the diffracted light is indicated in arbitrary units. The crystal plane orientation is shown in parentheses.

  As shown in FIG. 7, the (111) plane orientation of CaO alone is indicated by a peak at a diffraction angle of 32.2 degrees. The (111) plane orientation of MgO alone is indicated by a peak with a diffraction angle of 36.9 degrees. The (111) plane orientation of SrO alone is indicated by a peak with a diffraction angle of 30.0 degrees. The (111) plane orientation of BaO alone is indicated by a peak with a diffraction angle of 27.9 degrees.

  The underlayer 91 according to the present embodiment includes MgO and at least two or more metal oxides selected from the group consisting of CaO, SrO, and BaO.

  As shown in FIG. 7, the point A is a peak in the (111) plane orientation of the base layer 91 formed of two of MgO and CaO. Point B is a peak in the (111) plane orientation of the underlying layer 91 formed of two of MgO and SrO. Point C is a peak in the (111) plane orientation of the underlying layer 91 formed of two of MgO and BaO.

  As shown in FIG. 7, the diffraction angle at point A is 36.1 degrees. Point A exists between the peak of the (111) plane orientation in the MgO simple substance that is the first metal oxide and the peak of the (111) plane orientation in the CaO simple substance that is the second metal oxide.

  The diffraction angle at point B is 35.7 degrees. Point B exists between the peak of the (111) plane orientation in the MgO simple substance that is the first metal oxide and the peak of the (111) plane orientation in the SrO simple substance that is the second metal oxide.

  The diffraction angle at point C is 35.4 degrees. The point C exists between the peak of the (111) plane orientation in the MgO simple substance that is the first metal oxide and the peak of the (111) plane orientation in the BaO simple substance that is the second metal oxide.

  As shown in FIG. 8, the point D is a peak in the (111) plane orientation of the base layer 91 formed of three of MgO, CaO, and SrO. Point E is a peak in the (111) plane orientation of the base layer 91 formed of three of MgO, CaO, and BaO. The point F is a peak in the (111) plane orientation of the base layer 91 formed of three of BaO, CaO, and SrO.

  That is, the point D corresponds to the diffraction angle of 36.9 degrees of the (111) plane orientation of MgO alone, which is the maximum diffraction angle of a single oxide, and SrO, which is the minimum diffraction angle, in the (111) plane orientation as a specific orientation plane. A peak exists at a diffraction angle of 33.4 degrees, which is between the diffraction angle of 30.0 degrees of a single (111) plane orientation. Similarly, peaks at points E and F exist at 32.8 degrees and 30.2 degrees between the maximum diffraction angle and the minimum diffraction angle, respectively.

  In the present embodiment, the plane orientation (111) is exemplified. However, the same applies to other plane orientations.

  The depth from the vacuum level of CaO, SrO, and BaO exists in a shallow region as compared with MgO. Therefore, when driving a PDP, when electrons existing in the energy levels of CaO, SrO, and BaO transition to the ground state of Xe ions, the number of electrons emitted by the Auger effect is less than the energy level of MgO. It is thought that it will increase compared to the case of transition.

  Further, as described above, the peak of the base layer 91 in the X-ray diffraction analysis is between the peak of the first metal oxide and the peak of the second metal oxide. That is, it is considered that the energy level of the base layer 91 exists between single metal oxides, and the number of electrons emitted by the Auger effect is larger than that in the case of transition from the energy level of MgO.

  As a result, the base layer 91 according to the present embodiment can exhibit better secondary electron emission characteristics compared to MgO alone. As a result, the sustain voltage can be reduced. In particular, the discharge voltage can be reduced when the Xe partial pressure as the discharge gas is increased in order to increase the luminance. That is, a low-voltage and high-luminance PDP 1 can be realized.

  The underlayer 91 is formed by a general thin film forming method such as a sputtering method or an EB vapor deposition method. In the present embodiment, the underlayer 91 is formed by EB vapor deposition. A deposition source as a target is arranged in a vacuum deposition chamber, and an electron beam is irradiated to the deposition source. The components of the vapor deposition source are evaporated by the energy of the electron beam, and a film is formed on the carried substrate. The degree of vacuum in the vacuum deposition chamber, the atmospheric gas, the irradiation intensity of the electron beam, and the like are adjusted as appropriate.

  The base layer 91 in this embodiment includes at least a first metal oxide and a second metal oxide. The first metal oxide is MgO, and the second metal oxide is one selected from the group consisting of CaO, SrO and BaO. A vapor deposition source is prepared with components having a desired concentration.

  For example, when the base layer 91 made of MgO and CaO is formed, a large number of pellet-shaped deposition sources having a thickness of about 2 mm and a diameter of about 5 mm are mixed by mixing MgO powder and CaO powder to a predetermined concentration and sintering. Make it. A film is formed on the test piece using this vapor deposition source, and the composition of the film is confirmed by separate analysis. An underlayer 91 having a desired concentration is produced using the vapor deposition source thus produced.

  Similarly, in the sputtering method or the like, the base layer 91 is formed by producing a target having a desired concentration.

Further, it is desirable that the base layer 91 contains aluminum. This is based on the following reason. As described above, in the present embodiment, reducing organic gas is introduced and exposed to the protective layer 9 in the sealing exhaust process. Aluminum in the underlayer 91 exists as alumina (Al ₂ O ₃ ), and the presence of alumina in the underlayer 91 promotes the oxidizing action of the reducing organic gas. For example, when ethylene is used as the reducing organic gas, generation of ethylene oxide proceeds by alumina. Since this reaction further promotes the generation of oxidation defects in the underlayer 91, the effect of lowering the voltage contributing to the image display discharge can be obtained.

  As a result of investigations by the inventors, it was confirmed that when 250 ppm by weight of aluminum was added to the base layer 91, the discharge voltage was reduced by about 5V compared to the case where aluminum was not present.

  In the present embodiment, the concentration of aluminum contained in the underlayer is 50 ppm or more and 5000 ppm or less by weight. When the concentration was lower than 50 ppm, the effect of promoting the oxidizing action of the reducing organic gas by aluminum was not sufficient. On the other hand, when the concentration is higher than 5000 ppm, there is a problem that the discharge voltage at the time of image display increases.

  The aluminum added to the underlayer 91 is preferably present on the surface of the discharge space, and the same effect can be expected even if alumina crystal particles are arranged as a part of aggregated particles 92 and crystal particles 92a described later.

[3-2. Aggregated particles 92]
Aggregated particles 92 are formed by aggregating a plurality of MgO crystal particles 92a, which are metal oxides. The agglomerated particles 92 are preferably distributed uniformly over the entire surface of the base layer 91. This is because the variation of the discharge voltage in the PDP 1 is reduced.

  The MgO crystal particles 92a can be manufactured by either a gas phase synthesis method or a precursor firing method. In the gas phase synthesis method, first, a metal magnesium material having a purity of 99.9% or more is heated in an atmosphere filled with an inert gas. Furthermore, metallic magnesium is directly oxidized by introducing a small amount of oxygen into the atmosphere. In this manner, MgO crystal particles 92a are produced.

In the precursor firing method, the MgO precursor is uniformly fired at a high temperature of 700 ° C. or higher. Next, by slowly cooling, MgO crystal particles 92a are produced. Examples of the precursor include magnesium alkoxide (Mg (OR) ₂ ), magnesium acetylacetone (Mg (acac) ₂ ), magnesium hydroxide (Mg (OH) ₂ ), magnesium carbonate (MgCO ₂ ), magnesium chloride (MgCl ₂ ). ), Magnesium sulfate (MgSO ₄ ), magnesium nitrate (Mg (NO ₃ ) ₂ ), or magnesium oxalate (MgC ₂ O ₄ ). Depending on the selected compound, it may usually take the form of a hydrate. Hydrate can also be used as a precursor. The compound as the precursor is adjusted so that the purity of magnesium oxide (MgO) obtained after firing is 99.95% or higher, desirably 99.98% or higher. If a certain amount of impurity elements such as various alkali metals, B, Si, Fe, and Al are mixed in the precursor compound, unnecessary interparticle adhesion and sintering occur during heat treatment. As a result, it becomes difficult to obtain highly crystalline MgO crystal particles. Therefore, it is preferable to prepare the precursor in advance, such as removing the impurity element from the compound.

  A dispersion is prepared by dispersing MgO crystal particles 92a obtained by any of the above methods in a solvent. Next, the dispersion is applied to the surface of the base layer 91 by a spray method, a screen printing method, an electrostatic coating method, or the like. Thereafter, the solvent is removed through a drying / firing process. Through the above steps, MgO crystal particles 92 a are fixed on the surface of the underlayer 91.

[3-2-1. Details of Aggregated Particle 92]
The aggregated particles 92 are those in which crystal particles 92a having a predetermined primary particle size are aggregated or necked. In other words, it is not bonded as a solid with a large bonding force, but a plurality of primary particles form an aggregate body due to static electricity, van der Waals force, etc., and due to external stimuli such as ultrasound , Part or all of them are bonded to such a degree that they become primary particles. As shown in FIG. 9, the aggregated particles 92 have a particle size of about 1 μm, and the crystal particles 92a preferably have a polyhedral shape having seven or more faces such as a tetrahedron and a dodecahedron. .

  Moreover, the particle size of the primary particles of the crystal particles 92a can be controlled by the generation conditions of the crystal particles 92a. For example, when a precursor such as magnesium carbonate or magnesium hydroxide is produced by firing, the particle size can be controlled by controlling the firing temperature or firing atmosphere. Generally, the firing temperature can be selected in the range of 700 ° C to 1500 ° C. By setting the firing temperature to a relatively high 1000 ° C. or higher, the particle size can be controlled to about 0.3 to 2 μm. Further, by heating the precursor, a plurality of primary particles are aggregated or necked in the production process, and aggregated particles 92 can be obtained.

  According to the experiments by the present inventors, the aggregated particles 92 in which a plurality of MgO crystal particles are agglomerated mainly confirms the effect of suppressing the “discharge delay” in the write discharge and the effect of improving the temperature dependency of the “discharge delay”. Has been. Aggregated particles 92 are excellent in initial electron emission characteristics as compared with underlayer 91. Therefore, in the present embodiment, the agglomerated particles 92 are arranged as an initial electron supply unit required at the time of discharge pulse rising.

  The “discharge delay” is considered to be mainly caused by a shortage of the amount of initial electrons that become a trigger emitted from the surface of the underlayer 91 into the discharge space 16 at the start of discharge. Therefore, in order to contribute to the stable supply of initial electrons to the discharge space 16, the agglomerated particles 92 are dispersedly arranged on the surface of the base layer 91. As a result, abundant electrons are present in the discharge space 16 at the rise of the discharge pulse, and the discharge delay can be eliminated. Therefore, such initial electron emission characteristics enable high-speed driving with good discharge response even when the PDP 1 has a high definition. In the configuration in which the metal oxide aggregated particles 92 are disposed on the surface of the underlayer 91, in addition to the effect of mainly suppressing the “discharge delay” in the write discharge, the effect of improving the temperature dependency of the “discharge delay” is also achieved. can get.

[4. Change of Underlayer 91]
As described above, the protective layer 9 according to the present embodiment includes the base layer 91 and the aggregated particles 92. The underlayer 91 includes at least a first metal oxide and a second metal oxide. The first metal oxide is MgO, and the second metal oxide is one selected from the group consisting of CaO, SrO and BaO.

  As a result of investigations by the inventors, it has been found that when the protective layer 9 is exposed to reducing organic gas during sealing exhaust, the following changes occur particularly in the base layer 91.

  The composition in the vicinity of the surface on the discharge space side of the underlayer 91 of the PDP 1 and the composition in the underlayer 91 (bulk) are different, and the concentration of the second metal oxide may be higher in the vicinity of the surface than in the film. found.

  Here, the bulk of the foundation layer 91 indicates a region deeper than the discharge space side surface by 200 nm or more. The above change occurs regardless of the presence or absence of the aggregated particles 92. That is, when the aggregated particles 92 are not present, the bulk is in the protective layer.

  In FIG. 10, the measurement result of the base layer 91 composition change of the protective layer 9 concerning this Embodiment is shown. The sample used here is an underlayer 91 made of MgO and CaO. Using pellets obtained by mixing and sintering MgO powder and CaO powder, a film was formed by EB vapor deposition.

  Sample 1 was a front plate formed by the above-described method. Concentration measurement was performed on the region of the underlayer.

  Sample 2 is a sample in which the front plate of sample 1 and the rear plate produced by the above-described method are arranged to face each other and a PDP is produced through a sealing / exhaust process without introducing a reducing organic gas. . That is, the process is the same as that of the present embodiment until the front plate and the back plate are arranged to face each other. The concentration measurement was performed on the region of the underlayer by cleaving the PDP of Sample 2.

  Sample 3 is a sample manufactured by the same manufacturing method as the PDP of the present embodiment. Similar to sample 2, the concentration measurement was performed on the region of the base layer by cleaving the PDP of sample 3.

  Sample 1-3 was prepared at the same time until the front plate was formed, and the concentration of CaO powder as the evaporation source was adjusted so that the concentration of Sample 1 was 12 atm%. In any sample, the measurement was performed in a region corresponding to the gap between adjacent discharge cells, that is, a region not affected by the discharge.

  These measurement results are shown in FIG. The Ca concentration was measured with a scanning X-ray photoelectron spectrometer (PHI Quantera SXM type) manufactured by ULVAC-PHI and defined as the ratio of Ca and Mg, Ca / (Ca + Mg) [atm%]. Note that there is about ± 0.5 atm% as an error in the measurement.

  The surface Ca concentration was measured as it was with a scanning X-ray photoelectron spectrometer, and the bulk Ca concentration was measured by sputtering the sample with a 1 keV Ar ion beam to about 200 nm.

  It can be seen that both the sample 1 and the sample 2 have a constant Ca concentration on the surface of the underlying layer and the bulk. That is, it can be seen that in the PDP similar to the conventional technique, the Ca concentration of the underlayer is constant in the film thickness direction, and there is no change from the state after the underlayer is formed.

  On the other hand, in the sample 3 which is the PDP 1 according to the present embodiment, it can be seen that the Ca concentration on the surface of the underlayer is higher than the concentration of the underlayer bulk. It was confirmed that Sample 3 was about 1.4 times higher.

  This indicates that, in the PDP 1 according to the present embodiment, the protective layer 9 including the base layer 91 was exposed to the reducing organic gas at a high temperature in the sealing / exhaust process, and Ca segregated to the surface. Conceivable.

  Similarly, Sample 4-6 having a different Ca concentration from Sample 1-3 was prepared, and the Ca concentration was measured. Sample 4 corresponds to sample 1, sample 5 corresponds to sample 2, and sample 6 corresponds to sample 3. That is, the sample 6 is the same PDP 1 as in the present embodiment.

  Samples 4-6 were prepared simultaneously until the front plate was formed, and the concentration of the CaO powder as the evaporation source was adjusted so that the concentration of Sample 4 was 6 atm%. In any sample, the measurement was performed in a region corresponding to the gap between adjacent discharge cells, that is, a region not affected by the discharge. The measurement results are shown in FIG. In Sample 6, as in Sample 3, it can be seen that the Ca concentration on the surface of the underlayer is higher than the concentration of the underlayer bulk. It was confirmed that Sample 6 was as high as 1.20 times.

  Thus, it can be seen from the results of Sample 3 and Sample 6 that the segregation of the Ca component on the surface of the base layer 91 appears more as the Ca concentration in the base layer 91 is higher.

  Furthermore, the distribution of Ca concentration in the depth direction of the underlayer 91 of the PDP 1 in the present embodiment was confirmed. The result is shown in FIG. The Ca concentration was expressed as Ca / (Ca + Mg) [atm%] using the same method as in FIG. In any sample, the film thickness of the underlayer is 700 nm.

  The sample name is the same sample as in FIG. A circle indicates sample 3 and a triangle indicates sample 6. From Sample 3 and Sample 6, it can be seen that in the PDP 1 in the present embodiment, the Ca concentration of the underlayer 91 is substantially constant in a region deeper than 200 nm in the film thickness direction.

  The above phenomenon occurs regardless of the presence or absence of the agglomerated particles 92.

[5. Prototype evaluation]
A plurality of PDPs having different underlayer configurations were produced. The PDP was filled with 60 kPa Xe and Ne mixed gas (Xe 15%). Sample A is composed of MgO and CaO. Sample B is composed of MgO and SrO. Sample C is composed of MgO and BaO. Sample D is composed of MgO, CaO and SrO. Sample E is composed of MgO, CaO, and BaO. The comparative example is composed of MgO alone.

  For samples A to E, the sustain voltage was measured. When the comparative example was 100, sample A was 90, sample B was 87, sample C was 85, sample D was 81, and sample E was 82. Samples A to E are PDPs manufactured by a normal manufacturing method. That is, samples A to E are PDPs manufactured by a manufacturing method that does not have a reducing organic gas introduction step.

  When the Xe partial pressure of the discharge gas is increased from 10% to 15%, the luminance increases by about 30%, but in the comparative example, the sustain voltage increases by about 10%.

  On the other hand, the sustain voltages of Sample A, Sample B, Sample C, Sample D, and Sample E were all reduced by about 10% to 20% from the comparative example.

  Next, the PDP 1 having the base layer 91 having the same configuration as the samples A to E was manufactured by the manufacturing method according to the present embodiment. The first temperature profile was used from the sealing step C1 to the discharge gas supply step C4.

  As an example of the reducing organic gas, propylene, cyclopropane, acetylene, and ethylene were used. The sustain voltage of the PDP 1 according to the present embodiment was about 5% lower than those of the samples A to E.

  Furthermore, before introducing the reducing organic gas, in the sealing step C1, nitrogen gas is allowed to flow as an inert gas so that the inside of the discharge space 16 is in a positive pressure state through the through-hole opened in the discharge space 16, and then When sealing was performed, it was about 5 to 7% lower than the sustain voltage of samples A to E.

[6. Summary]
The method for manufacturing PDP 1 disclosed in the present embodiment includes the following steps. The protective layer 9 is exposed to the reducing organic gas by introducing a gas containing the reducing organic gas into the discharge space. Next, reducing organic gas is discharged from the discharge space. Next, the discharge gas is sealed in the discharge space.

  In the protective layer 9 exposed to the reducing organic gas, oxygen deficiency occurs. Oxygen deficiency is considered to improve the secondary electron emission ability of the protective layer. Therefore, the PDP 1 manufactured by the manufacturing method according to the present embodiment can reduce the sustain voltage.

  Furthermore, the reducing organic gas is preferably a hydrocarbon-based gas that does not contain oxygen. This is because the reduction ability is enhanced by not containing oxygen.

  Further, the reducing organic gas is preferably at least one selected from acetylene, ethylene, methylacetylene, propadiene, propylene, cyclopropane, propane and butane. This is because the reducing organic gas is easy to handle in the manufacturing process. Furthermore, it is because said reducing organic gas is easy to decompose | disassemble.

  In the present embodiment, a manufacturing method in which a gas containing a reducing organic gas is introduced into the discharge space after the discharge space is exhausted is exemplified. However, the gas containing the reducing organic gas can be introduced into the discharge space by continuously supplying the gas containing the reducing organic gas to the discharge space without exhausting the discharge space.

  When the protective layer 9 includes the metal oxide crystal particles 92 a or the aggregated particles 92 in which a plurality of metal oxide crystal particles 92 a are aggregated on the base layer 91, the protective layer 9 has a high charge holding capability and a high electron emission capability. Therefore, as a whole PDP 1, high-speed driving can be realized with a low voltage even with a high-definition PDP. In addition, high-quality image display performance with reduced lighting failure can be realized.

  Moreover, in this Embodiment, MgO was illustrated as a metal oxide crystal particle. However, even with other single crystal particles, similar effects can be obtained by using crystal particles made of metal oxides such as Sr, Ca, Ba, Al, etc., which have high electron emission performance like MgO. Thus, the metal oxide crystal particles are not limited to MgO.

  As described above, the technology disclosed in the present embodiment is useful for realizing a PDP having high-definition and high-luminance display performance and low power consumption.

1 PDP
DESCRIPTION OF SYMBOLS 2 Front plate 3 Front glass substrate 4 Scan electrode 4a, 5a Transparent electrode 4b, 5b Metal bus electrode 5 Sustain electrode 6 Display electrode 7 Black stripe 8 Dielectric layer 9 Protection layer 10 Back plate 11 Back glass substrate 12 Data electrode 13 Base dielectric Body layer 14 Partition 15 Phosphor layer 16 Discharge space 91 Underlayer 92 Aggregated particle 92a Crystal particle

Claims (8)

A front plate having a display electrode pair, a dielectric layer, and a protective layer, and a rear plate are disposed opposite to each other to form a discharge space
The protective layer includes at least a first metal oxide and a second metal oxide,
The first metal oxide is magnesium oxide;
The second metal oxide is one of calcium oxide, strontium oxide, and barium oxide,
The protective layer contains aluminum,
The plasma display panel, wherein the concentration of the second metal oxide on the discharge space side of the protective layer is higher than the concentration in the protective layer. The plasma display panel according to claim 1, wherein the protective layer contains aluminum in a weight ratio of 50 ppm or more and 5000 ppm or less. The region of the protective layer corresponding to a gap between adjacent display electrode pairs, the second metal oxide concentration on the discharge space side of the protective layer is higher than the concentration in the protective layer. The plasma display panel as described. The protective layer has at least one peak in X-ray diffraction analysis,
The peak is between a first peak in an X-ray diffraction analysis of the first metal oxide and a second peak in an X-ray diffraction analysis of the second metal oxide;
The plasma display panel according to claim 1 or 2, wherein the first peak and the second peak have the same plane orientation as the plane orientation indicated by the peak. A method of manufacturing a plasma display panel in which a front plate and a rear plate having a protective layer are formed in a discharge space, and are disposed opposite to each other and sealed, and the discharge space is exhausted.
The protective layer includes at least a first metal oxide and a second metal oxide,
The first metal oxide is magnesium oxide;
The second metal oxide is one of calcium oxide, strontium oxide, and barium oxide,
The protective layer contains aluminum,
The second metal oxide concentration on the discharge space side of the protective layer is higher than the concentration in the protective layer,
A method for manufacturing a plasma display panel, wherein a reducing organic gas is exposed to a surface of the protective layer after the protective layer is formed. The said protective layer is a manufacturing method of the plasma display panel of Claim 4 containing 50 ppm or more and 5000 ppm or less by weight of aluminum. The front plate on which the protective layer is formed and the back plate are arranged opposite to each other to form the discharge space,
Exhausting the gas in the discharge space;
Introducing a reducing organic gas into the discharge space to expose the protective layer;
The method of manufacturing a plasma display panel according to claim 4, wherein the reducing organic gas is exhausted. The reducing organic gas is at least one selected from acetylene, ethylene, methylacetylene, propadiene, propylene, cyclopropane, propane and butane.
The manufacturing method of the plasma display panel of Claim 5.

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