JP2010192357A - Method of manufacturing plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma display panel of high-definition/high-luminance display performance and low power consumption. <P>SOLUTION: A method of manufacturing a plasma display panel has a sealing step of placing a front plate 2 and a rear plate 10 opposite each other and sealing their edge portions with a sealant member. A protective layer 9 for the front plate 2 is formed from metal oxides selected from magnesium oxides, calcium oxides, strontium oxides and barium oxides. The sealing step has a holding step of flowing a dried gas through a through-hole opened in a discharge space provided in the rear plate 10 so as to put the discharge space under a positive pressure and hold the discharge space in a positive pressure condition, and an exhaustion step of increasing an amount of the dried gas flowing therein and exhausting the gas within the discharge space after the holding step. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a plasma display panel used for a display device or the like.

  A plasma display panel (hereinafter referred to as a PDP) can realize a high definition and a large screen, and thus a 100-inch class television or the like has been commercialized. In recent years, PDP has been applied to high-definition televisions that have more than twice the number of scanning lines compared to the conventional NTSC system. In response to energy problems, efforts to further reduce power consumption and environmental issues There is also a growing demand for PDPs that do not contain lead components in consideration of the above.

  A PDP basically includes a front plate and a back plate. The front plate is a glass substrate of sodium borosilicate glass produced by the float process, a display electrode composed of a striped transparent electrode and a bus electrode formed on one main surface of the glass substrate, A dielectric layer that covers the display electrode and functions as a capacitor, and a protective layer made of magnesium oxide (MgO) formed on the dielectric layer.

  On the other hand, the back plate is a glass substrate, stripe-shaped address electrodes formed on one main surface thereof, a base dielectric layer covering the address electrodes, a partition formed on the base dielectric layer, The phosphor layer is formed between the barrier ribs and emits red, green and blue light.

  The front plate and the back plate are hermetically sealed with their electrode forming surfaces facing each other, and neon (Ne) -xenon (Xe) discharge gas is sealed at a pressure of 400 Torr to 600 Torr in a discharge space partitioned by a partition wall. ing. PDP discharges by selectively applying a video signal voltage to the display electrodes, and the ultraviolet rays generated by the discharge excite each color phosphor layer to emit red, green, and blue light, thereby realizing color image display is doing.

  In addition, such a PDP driving method includes an initialization period in which wall charges are adjusted so that writing is easy, a writing period in which writing discharge is performed according to an input image signal, and a discharge space in which writing is performed. A driving method having a sustain period in which display is performed by generating a sustain discharge is generally used. A period (subfield) obtained by combining these periods is repeated a plurality of times within a period (one field) corresponding to one frame of an image, thereby performing PDP gradation display.

  In such a PDP, the role of the protective layer formed on the dielectric layer of the front plate is to protect the dielectric layer from ion bombardment due to discharge and to emit initial electrons for generating address discharge. Etc. Protecting the dielectric layer from ion bombardment plays an important role in preventing an increase in discharge voltage, and emitting initial electrons for generating an address discharge is an address discharge error that causes image flickering. It is an important role to prevent.

In order to increase the number of initial electrons emitted from the protective layer and reduce image flickering, for example, examples of adding impurities to the MgO protective layer and examples of forming MgO particles on the MgO protective layer are disclosed. (For example, see Patent Documents 1, 2, 3, 4, 5, etc.).
JP 2002-260535 A JP 11-339665 A JP 2006-59779 A JP-A-8-236028 JP-A-10-334809

  In recent years, high definition has been advanced in televisions, and a low-cost, low-power-consumption, high-brightness full HD (high definition) (1920 × 1080 pixels: progressive display) PDP is required in the market. Since the electron emission characteristics from the protective layer determine the image quality of the PDP, it is very important to control the electron emission characteristics.

  That is, in order to display a high-definition image, the number of pixels to be written increases even though the time of one field is constant. Therefore, in the writing period in the subfield, the pulse applied to the address electrode It is necessary to reduce the width. However, there is a time lag called “discharge delay” from the rise of the voltage pulse to the occurrence of discharge in the discharge space, so if the pulse width is narrowed, the probability that the discharge can be completed within the writing period is low. End up. As a result, lighting failure occurs, and the problem of deterioration in image quality performance such as flickering occurs.

  As described above, in order to advance the high definition and low power consumption of the PDP, it is necessary to simultaneously realize that the discharge voltage is not increased and that the image quality is improved by reducing defective lighting. There was a problem.

  The present invention has been made in view of such a problem, and an object of the present invention is to realize a PDP having high luminance display performance and capable of being driven at a low voltage.

  In order to achieve the above object, a PDP of the present invention includes a first substrate having a dielectric layer formed so as to cover a display electrode formed on a substrate and a protective layer formed on the dielectric layer, An address electrode is formed in a direction intersecting with the display electrode of the first substrate and a partition wall for partitioning the discharge space is provided so as to form a discharge space filled with a discharge gas on the first substrate. A method of manufacturing a plasma display panel, comprising: a second substrate; and a sealing step in which the first substrate and the second substrate are arranged to face each other and a peripheral portion is sealed with a sealing member. The protective layer of one substrate is formed of a metal oxide selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide, and the sealing step includes a through-hole that opens into the discharge space A holding step of allowing the drying gas to flow into the discharge space and holding the discharge space in a positive pressure state, and after this holding step, increasing the amount of inflow of the drying gas and discharging the gas in the discharge space And a discharging process.

  According to the present invention, it is possible to reduce the discharge start voltage even when the Xe gas partial pressure of the discharge gas is increased in order to improve the secondary electron emission characteristics in the protective layer and increase the luminance. A PDP excellent in display performance capable of being driven with high brightness and low voltage can be realized. In addition, the reaction between the protective film and the impurity gas during the panel manufacturing process can be suppressed, and a PDP in which variation in discharge characteristics for each discharge cell is suppressed can be realized. Furthermore, a PDP with less display unevenness can be realized.

  Hereinafter, a PDP according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing the structure of a PDP according to an embodiment of the present invention. The basic structure of the PDP is the same as that of a general AC surface discharge type PDP. As shown in FIG. 1, in the PDP 1, a front plate 2 as a first substrate made of a front glass substrate 3 and the like and a back plate 10 as a second substrate made of a back glass substrate 11 and the like are arranged to face each other. The peripheral part of the front plate 2 and the back plate 10 is hermetically sealed by a sealing member made of glass frit or the like. The discharge space 16 inside the sealed PDP 1 is filled with a discharge gas in which Ne or the like is mixed with Xe having a pressure of 30 Torr to 300 Torr.

  On the front glass substrate 3 of the front plate 2, a pair of strip-shaped display electrodes 6 each composed of the scanning electrodes 4 and the sustain electrodes 5 and a plurality of black stripes (light shielding layers) 7 are arranged in parallel to each other. A dielectric layer 8 is formed on the front glass substrate 3 so as to cover the display electrodes 6 and the light-shielding layer 7 so as to hold charges and function as a capacitor. A protective layer 9 is further formed thereon. .

  On the back glass substrate 11 of the back plate 10, a plurality of strip-like address electrodes 12 are arranged in parallel to each other in a direction orthogonal to the scanning electrodes 4 and the sustain electrodes 5 of the front plate 2. Layer 13 is covering. Further, a partition wall 14 having a predetermined height is formed on the base dielectric layer 13 between the address electrodes 12 to divide the discharge space 16. In each groove between the barrier ribs 14, a phosphor layer 15 that emits red, green, and blue light by ultraviolet rays is sequentially applied. A discharge space is formed at a position where the scan electrode 4 and the sustain electrode 5 intersect with the address electrode 12, and a discharge space having red, green, and blue phosphor layers 15 arranged in the direction of the display electrode 6 is used for color display. Become a pixel.

FIG. 2 is a cross-sectional view showing a detailed configuration of the front plate 2 of the PDP 1 in the embodiment of the present invention, and FIG. 2 is shown upside down with respect to FIG. As shown in FIG. 2, a display electrode 6 and a light shielding layer 7 including scanning electrodes 4 and sustaining electrodes 5 are formed in a pattern on a front glass substrate 3 manufactured by a float method or the like. Scan electrode 4 and sustain electrode 5 are transparent electrodes 4a and 5a made of indium tin oxide (ITO), tin oxide (SnO ₂ ), etc., and metal bus electrodes 4b and 5b formed on transparent electrodes 4a and 5a, respectively. It is comprised by. The metal bus electrodes 4b and 5b are used for the purpose of imparting conductivity in the longitudinal direction of the transparent electrodes 4a and 5a, and are formed of a conductive material whose main component is a silver (Ag) material.

  The dielectric layer 8 includes a first dielectric layer 81 provided on the front glass substrate 3 so as to cover the transparent electrodes 4a and 5a, the metal bus electrodes 4b and 5b, and the light shielding layer 7, and a first dielectric. The second dielectric layer 82 formed on the layer 81 has at least two layers, and the protective layer 9 is formed on the second dielectric layer 82.

  The protective layer 9 includes a base film 91 formed on the dielectric layer 8 and aggregated particles 92 in which a plurality of magnesium oxide (MgO) crystal particles 92 a are aggregated on the base film 91. In the protective layer 9, the base film 91 is formed of a metal oxide selected from magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). The base film 91 of the protective layer 9 is made of a metal oxide composed of at least two oxides selected from magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). It is desirable to form.

  FIG. 3 is a flowchart showing the manufacturing process of the PDP. As shown in FIG. 3, the PDP is outside the image display area of the back plate 10 created by the front plate creating process, the back plate creating process, and the back plate creating process. A glass frit as a sealing member is applied, and then a frit coating process in which the glass frit is pre-baked at a temperature of about 350 ° C. in order to remove resin components, etc. The sealing step of pasting and sealing the back plate 10 that has finished the process, the exhausting process of exhausting the gas in the discharge space thereafter, and Ne and Xe as the main components in the evacuated panel thereafter The panel is completed through a discharge gas supply process for supplying the discharge gas.

Here, the sealing member is preferably a frit mainly composed of bismuth oxide or vanadium oxide. 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 one 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 mainly composed of vanadium oxide, for example, a filler made of an oxide such as Al ₂ O ₃ , SiO ₂ or cordierite is added to a V ₂ O ₅ —BaO—TeO—WO glass material. Things can be used.

  Next, the front plate creation process will be described. First, the scan electrode 4, the sustain electrode 5, and the light shielding layer 7 are formed on the front glass substrate 3. Transparent electrodes 4a and 5a and metal bus electrodes 4b and 5b constituting scan electrode 4 and sustain electrode 5 are formed by patterning using a photolithography method or the like. The transparent electrodes 4a and 5a are formed using a thin film process or the like, and the metal bus electrodes 4b and 5b are solidified by baking a paste containing a silver (Ag) material at a predetermined temperature. Similarly, the light shielding layer 7 is also formed by screen printing a paste containing a black pigment or by forming a black pigment on the entire surface of the glass substrate and then patterning and baking using a photolithography method.

  Next, a dielectric paste is applied on the front glass substrate 3 by a die coating method or the like so as to cover the scan electrode 4, the sustain electrode 5, and the light shielding layer 7, thereby forming a dielectric paste (dielectric material) layer. After the dielectric paste is applied, the surface of the applied dielectric paste is leveled by leaving it to stand for a predetermined time, so that a flat surface is obtained. Thereafter, the dielectric paste layer is formed by baking and solidifying the dielectric paste layer to cover the scan electrode 4, the sustain electrode 5, and the light shielding layer 7. The dielectric paste is a paint containing a dielectric material such as glass powder, a binder and a solvent.

  Next, a base film 91 is formed on the dielectric layer 8. In the embodiment of the present invention, the base film 91 is made of at least two oxides selected from magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). It is formed of a metal oxide.

  The base film 91 is formed into a thin film using a pellet made of a single material of magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO), or a pellet obtained by mixing these materials. Formed by the method. As a thin film forming method, a known method such as an electron beam evaporation method, a sputtering method, or an ion plating method can be applied. As an example, it can be considered that the upper limit of the pressure that can be actually taken is 1 Pa in the sputtering method and 0.2 Pa in the electron beam evaporation method which is an example of the evaporation method. In addition, as an atmosphere during film formation of the base film 91, a predetermined electron emission characteristic is obtained by adjusting the atmosphere during film formation in a sealed state that is shut off from the outside in order to prevent moisture adhesion and adsorption of impurities. A base film 91 made of a metal oxide having the above can be formed.

  Next, the agglomerated particles 92 of the magnesium oxide (MgO) crystal particles 92a deposited on the base film 91 will be described. These crystal particles 92a can be manufactured by any one of the following vapor phase synthesis method or precursor baking method. In the gas phase synthesis method, a magnesium metal material having a purity of 99.9% or more is heated in an atmosphere filled with an inert gas, and a small amount of oxygen is introduced into the atmosphere to directly oxidize magnesium, thereby oxidizing the material. Magnesium (MgO) crystal particles 92a can be produced.

On the other hand, in the precursor firing method, the crystal particles 92a can be produced by the following method. In the precursor firing method, a magnesium oxide (MgO) precursor is uniformly fired at a high temperature of 700 ° C. or higher, and this is gradually cooled to obtain magnesium oxide (MgO) crystal particles 92a. Examples of the precursor include magnesium alkoxide (Mg (OR) ₂ ), magnesium acetylacetone (Mg (acac) ₂ ), magnesium hydroxide (Mg (OH) ₂ ), magnesium carbonate (MgCO ₂ ), and 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, but such a hydrate may be used.

  These compounds are adjusted so that the purity of magnesium oxide (MgO) obtained after firing is 99.95% or more, preferably 99.98% or more. If these compounds contain a certain amount or more of various kinds of alkali metals, B, Si, Fe, Al and other impurity elements, unnecessary interparticle adhesion and sintering will occur during heat treatment, resulting in highly crystalline magnesium oxide ( This is because it is difficult to obtain MgO) crystal particles. For this reason, it is necessary to adjust the precursor in advance by removing the impurity element.

  The magnesium oxide (MgO) crystal particles 92a obtained by any of the above methods are dispersed in a solvent, and the dispersion is applied to the undercoat film 91 by a spray method, a screen printing method, a slit coating method, an electrostatic coating method, or the like. Disperse the surface. Thereafter, the solvent is removed through a drying / firing process, and the magnesium oxide (MgO) crystal particles 92 a can be fixed on the surface of the base film 91.

  As a method for dispersing and fixing the magnesium oxide (MgO) crystal particles 92 a on the surface of the base film 91, a method that can be performed at a low temperature of 400 ° C. or lower is preferable from the viewpoint of suppressing reaction with impurities in the base film 91. .

  Through such a series of steps, predetermined components (scanning electrode 4, sustaining electrode 5, light shielding layer 7, dielectric layer 8, and protective layer 9) are formed on front glass substrate 3, and front plate 2 is completed.

  On the other hand, in the back plate creating process, the back plate 10 is formed as follows. First, the structure for the address electrode 12 is formed by a method of screen printing a paste containing silver (Ag) material on the rear glass substrate 11 or a method of patterning using a photolithography method after forming a metal film on the entire surface. A material layer to be a material is formed. Thereafter, the address electrode 12 is formed by firing at a predetermined temperature. Next, a dielectric paste is applied on the rear glass substrate 11 on which the address electrodes 12 are formed by a die coating method or the like so as to cover the address electrodes 12 to form a dielectric paste layer. Thereafter, the base dielectric layer 13 is formed by firing the dielectric paste layer. The dielectric paste is a paint containing a dielectric material such as glass powder, a binder and a solvent.

  Next, a partition wall forming paste containing a partition wall material is applied on the base dielectric layer 13 and patterned into a predetermined shape to form a partition wall material layer. Then, the partition 14 is formed by baking at a predetermined temperature. Here, as a method of patterning the partition wall paste applied on the base dielectric layer 13, a photolithography method or a sand blast method can be used. Then, the phosphor layer 15 is formed by applying and baking a phosphor paste containing a phosphor material on the base dielectric layer 13 between the adjacent barrier ribs 14 and on the side surfaces of the barrier ribs 14. Through the above steps, the back plate 10 having predetermined components on the back glass substrate 11 is completed.

Here, the first dielectric layer 81 and the second dielectric layer 82 constituting the dielectric layer 8 of the front plate 2 will be described in detail. The dielectric material of the first dielectric layer 81 is composed of the following material composition. Specifically, bismuth oxide (Bi ₂ O ₃ ) is 20 wt% to 40 wt%, and at least one selected from calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) is 0.5 wt% to 12 wt%. Including 0.1% by weight to 7% by weight of at least one selected from molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), cerium oxide (CeO ₂ ), and manganese dioxide (MnO ₂ ). .

In addition, instead of molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), cerium oxide (CeO ₂ ), manganese dioxide (MnO ₂ ), copper oxide (CuO), chromium oxide (Cr ₂ O ₃ ), cobalt oxide At least one selected from (Co ₂ O ₃ ), vanadium oxide (V ₂ O ₇ ), and antimony oxide (Sb ₂ O ₃ ) may be contained in an amount of 0.1 wt% to 7 wt%.

Further, as components other than the above, zinc oxide (ZnO) is 0 wt% to 40 wt%, boron oxide (B ₂ O ₃ ) is 0 wt% to 35 wt%, and silicon oxide (SiO ₂ ) is 0 wt% to A material composition that does not contain a lead component, such as 15 wt% and aluminum oxide (Al ₂ O ₃ ) 0 wt% to 10 wt% may be included.

  A dielectric material powder is produced by pulverizing a dielectric material composed of these composition components with a wet jet mill or a ball mill so as to have a particle size of 0.5 μm to 2.5 μm. Next, 55 wt% to 70 wt% of the dielectric material powder and 30 wt% to 45 wt% of the binder component are well kneaded with three rolls to paste for the first dielectric layer 81 for die coating or printing. Is made.

  The binder component is ethyl cellulose, terpineol containing 1% to 20% by weight of acrylic resin, or butyl carbitol acetate. In addition, dioctyl phthalate, dibutyl phthalate, triphenyl phosphate and tributyl phosphate are added to the paste as needed, and glycerol monooleate, sorbitan sesquioleate, homogenol (Kao Corporation) as a dispersant. The printing property may be improved as a paste by adding a phosphate ester of an alkyl allyl group, etc.

  Next, using this first dielectric layer paste, the front glass substrate 3 is printed by a die coat method or a screen printing method so as to cover the display electrode 6 and dried, and then slightly higher than the softening point of the dielectric material. The first dielectric layer 81 is formed by firing at a temperature of 575 ° C. to 590 ° C.

Next, the second dielectric layer 82 will be described. The dielectric material of the second dielectric layer 82 is composed of the following material composition. That is, bismuth oxide (Bi ₂ O ₃ ) is 11 wt% to 20 wt%, and at least one selected from calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) is 1.6 wt%. wherein to 21 wt%, molybdenum oxide _(MoO 3), tungsten oxide _(WO 3), and includes at least one of 0.1 wt% to 7 wt% selected from cerium oxide (CeO _2).

Note that instead of molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), and cerium oxide (CeO ₂ ), copper oxide (CuO), chromium oxide (Cr ₂ O ₃ ), cobalt oxide (Co ₂ O ₃ ), At least one selected from vanadium oxide (V ₂ O ₇ ), antimony oxide (Sb ₂ O ₃ ), and manganese oxide (MnO ₂ ) may be contained in an amount of 0.1 wt% to 7 wt%.

Further, as components other than the above, zinc oxide (ZnO) is 0 wt% to 40 wt%, boron oxide (B ₂ O ₃ ) is 0 wt% to 35 wt%, and silicon oxide (SiO ₂ ) is 0 wt% to A material composition that does not contain a lead component, such as 15 wt% and aluminum oxide (Al ₂ O ₃ ) 0 wt% to 10 wt% may be included.

  A dielectric material powder is produced by pulverizing a dielectric material composed of these composition components with a wet jet mill or a ball mill so as to have a particle size of 0.5 μm to 2.5 μm. Next, 55 wt% to 70 wt% of the dielectric material powder and 30 wt% to 45 wt% of the binder component are well kneaded with three rolls to obtain a second dielectric layer paste for die coating or printing. Make it. The binder component is ethyl cellulose, terpineol containing 1% to 20% by weight of acrylic resin, or butyl carbitol acetate. In the paste, dioctyl phthalate, dibutyl phthalate, triphenyl phosphate, and tributyl phosphate are added as plasticizers as needed, and glycerol monooleate, sorbitan sesquioleate, and homogenol (Kao Corporation) as dispersants. The printability may be improved by adding a phosphoric ester of an alkyl allyl group or the like.

  Next, using this second dielectric layer paste, printing is performed on the first dielectric layer 81 by screen printing or die coating, followed by drying, and then a temperature slightly higher than the softening point of the dielectric material is 550 ° C. Bake at 590 ° C.

The film thickness of the dielectric layer 8 is preferably set to 41 μm or less in total of the first dielectric layer 81 and the second dielectric layer 82 in order to ensure visible light transmittance. The first dielectric layer 81, bismuth oxide of the metal bus electrodes 4b, bismuth oxide in order to suppress the reaction between 5b silver _{(Ag) (Bi 2 O 3} ) content of second dielectric layer 82 It is more than the content of (Bi ₂ O ₃ ) and is 20 wt% to 40 wt%. Therefore, since the visible light transmittance of the first dielectric layer 81 is lower than the visible light transmittance of the second dielectric layer 82, the film thickness of the first dielectric layer 81 is set to the film thickness of the second dielectric layer 82. It is thinner.

The second dielectric layer 82 is less likely to be colored when the content of bismuth oxide (Bi ₂ O ₃ ) is 11% by weight or less, but bubbles are likely to be generated in the second dielectric layer 82. Therefore, it is not preferable. On the other hand, if the content exceeds 40% by weight, coloration tends to occur, and the transmittance decreases.

  In addition, the smaller the film thickness of the dielectric layer 8, the more remarkable the effect of improving the luminance and reducing the discharge voltage. Therefore, it is desirable to set the film thickness as small as possible within the range where the withstand voltage does not decrease. From such a viewpoint, in the embodiment of the present invention, the thickness of the dielectric layer 8 is set to 41 μm or less, the first dielectric layer 81 is set to 5 μm to 15 μm, and the second dielectric layer 82 is set to 20 μm to 36 μm. Yes.

  The PDP manufactured in this manner has little coloring phenomenon (yellowing) of the front glass substrate 3 even when a silver (Ag) material is used for the display electrode 6, and bubbles are generated in the dielectric layer 8. Thus, the dielectric layer 8 having excellent withstand voltage performance can be realized.

  Next, the detail of the protective layer 9 in embodiment of this invention is demonstrated. In the PDP in the embodiment of the present invention, as shown in FIG. 2, the protective layer 9 includes a base film 91 formed on the dielectric layer 8 and magnesium oxide (MgO) crystal particles deposited on the base film 91. 92a is constituted by agglomerated particles 92 in which a plurality of agglomerated particles 92 are agglomerated. Further, the base film 91 is formed of a metal oxide made of at least two oxides selected from magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO), In the X-ray diffraction analysis of the surface of the base film 91, the metal oxide has a peak between the minimum diffraction angle and the maximum diffraction angle generated from a single oxide constituting the metal oxide of a specific orientation plane. Yes.

  FIG. 4 is a diagram showing an X-ray diffraction result on the surface of the base film 91 constituting the protective layer 9 of the PDP in the embodiment of the present invention. FIG. 4 also shows the results of X-ray diffraction analysis of magnesium oxide (MgO) alone, calcium oxide (CaO) alone, strontium oxide (SrO) alone, and barium oxide (BaO) alone.

  In FIG. 4, the horizontal axis represents the Bragg diffraction angle (2θ), and the vertical axis represents the intensity of the X-ray diffraction wave. The unit of the diffraction angle is shown in degrees when one round is 360 degrees, and the intensity is shown in an arbitrary unit. In the figure, the crystal orientation plane which is a specific orientation plane is shown in parentheses. As shown in FIG. 4, with respect to the crystal orientation plane (111), the diffraction angle is 32.2 degrees for calcium oxide (CaO) alone, the diffraction angle is 36.9 degrees for magnesium oxide (MgO) alone, and the diffraction angle for strontium oxide alone. It can be seen that 30.0 degrees and barium oxide alone has a peak at a diffraction angle of 27.9 degrees.

  In the PDP in the embodiment of the present invention, at least two or more selected from magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) are used as the base film 91 of the protective layer 9. It is formed of a metal oxide made of the oxide.

  FIG. 4 shows an X-ray diffraction result when the single component constituting the base film 91 is two components. That is, the X-ray diffraction result of the base film 91 formed using magnesium oxide (MgO) and calcium oxide (CaO) alone was formed using point A, magnesium oxide (MgO) and strontium oxide (SrO) alone. The X-ray diffraction result of the base film 91 is indicated by B point, and further, the X-ray diffraction result of the base film 91 formed using magnesium oxide (MgO) and barium oxide (BaO) alone is indicated by C point.

  That is, the point A is a diffraction angle of 36.9 degrees of the magnesium oxide (MgO) alone, which is the maximum diffraction angle of the single oxide, in the crystal orientation plane (111) as the specific orientation plane, and the oxidation which is the minimum diffraction angle. A peak exists at a diffraction angle of 36.1 degrees, which is between the diffraction angle of 32.2 degrees of calcium (CaO) alone. Similarly, peaks at points B and C exist at 35.7 degrees and 35.4 degrees between the maximum diffraction angle and the minimum diffraction angle, respectively.

  Further, FIG. 5 shows the X-ray diffraction result when the single component constituting the base film 91 is three or more components, as in FIG. That is, FIG. 5 shows the results when magnesium oxide (MgO), calcium oxide (CaO), and strontium oxide (SrO) are used as the single component, point D, magnesium oxide (MgO), calcium oxide (CaO), and oxidation. The results when barium (BaO) is used are indicated by point E, and the results when calcium oxide (CaO), strontium oxide (SrO) and barium oxide (BaO) are used are indicated by point F.

  That is, the point D is a crystal orientation plane (111) as a specific orientation plane, and a diffraction angle of 36.9 degrees of magnesium oxide (MgO) as a maximum diffraction angle of a single oxide and an oxidation level as a minimum diffraction angle. A peak exists at a diffraction angle of 33.4 degrees, which is between the diffraction angle of 30.0 degrees of strontium (SrO) alone. 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.

  Therefore, in the X-ray diffraction analysis of the surface of the base film 91 of the metal oxide constituting the base film 91, the base film 91 of the PDP in the embodiment of the present invention has two components or three components as a single component. A peak exists between the minimum diffraction angle and the maximum diffraction angle of a peak generated from a single oxide constituting a metal oxide having a specific orientation plane.

  In the above description, (111) has been described as the crystal orientation plane as the specific orientation plane, but the peak position of the metal oxide is the same as that described above when other crystal orientation planes are also targeted.

  The depth from the vacuum level of calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) exists in a shallow region as compared with magnesium oxide (MgO). Therefore, when the PDP 1 is driven, when electrons existing in the energy levels of calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) transition to the ground state of the xenon (Xe) ion, Auger It is considered that the number of electrons emitted due to the effect increases as compared with the case of transition from the energy level of magnesium oxide (MgO).

  Further, as described above, the base film 91 according to the embodiment of the present invention has a peak between the minimum diffraction angle and the maximum diffraction angle of the peak generated from the single oxide constituting the metal oxide. I have to. As a result of the X-ray diffraction analysis, the metal oxide having the characteristics shown in FIGS. 4 and 5 has its energy level between the single oxides constituting them. Accordingly, the energy level of the base film 91 is also present between the single oxides, and the amount of energy acquired by other electrons due to the Auger effect can be set to an amount sufficient to be released beyond the vacuum level. .

  As a result, the base film 91 can exhibit better secondary electron emission characteristics as compared with magnesium oxide (MgO) alone, and as a result, the discharge sustaining voltage can be reduced. Therefore, particularly when the partial pressure of xenon (Xe) as the discharge gas is increased in order to increase the luminance, it is possible to reduce the discharge voltage and realize a low-voltage and high-luminance PDP.

  Here, in the PDP according to the embodiment of the present invention, the discharge sustaining voltage of the PDP when the configuration of the base film 91 is changed will be described. First, as a sample according to the present invention, sample A (underlying film 91 is a metal oxide of magnesium oxide (MgO) and calcium oxide (CaO)), and sample B (underlying film 91 is magnesium oxide (MgO) and strontium oxide (SrO). ), Sample C (the base film 91 is a metal oxide of magnesium oxide (MgO) and barium oxide (BaO)), sample D (the base film 91 is magnesium oxide (MgO), calcium oxide (CaO)) And metal oxide by strontium oxide (SrO)), sample E (underlying film 91 is a metal oxide by magnesium oxide (MgO), calcium oxide (CaO) and barium oxide (BaO)), and as a comparative example, Prepared the base film 91 composed of magnesium oxide (MgO) alone It was.

  When the sustaining voltage is measured for these samples A to E, when the comparative example is 100, sample A is 90, sample B is 87, sample C is 85, sample D is 81, and sample E is 82. The value is shown.

  When the partial pressure of the discharge gas xenon (Xe) is increased from 10% to 15%, the luminance increases by about 30%. However, in the comparative example in which the base film 91 is made of magnesium oxide (MgO) alone, the discharge is maintained. The voltage increases about 10%. On the other hand, in the PDP according to the embodiment of the present invention, the discharge sustaining voltage can be reduced by about 10% to 20% in all of the samples A, B, C, D, and E as compared with the comparative example. Therefore, the discharge start voltage can be set within the normal operation range, and a high-luminance and low-voltage drive PDP can be realized.

  Calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) are highly reactive as a single substance, and thus easily react with impurities, and as a result, the electron emission performance tends to decrease. By forming the structure, the reactivity is reduced, and the crystal structure is formed with less impurity contamination and less oxygen vacancies, so that excessive emission of electrons during driving of the PDP is suppressed, and low voltage driving In addition to the coexistence effect of secondary electron emission performance, the effect of moderate electron retention characteristics is also exhibited. This charge retention characteristic is particularly effective for retaining wall charges stored during the initialization period and preventing write defects during the write period to perform reliable write discharge.

  Next, the agglomerated particles 92 in which a plurality of magnesium oxide (MgO) crystal particles 92a are aggregated provided on the base film 91 in the embodiment of the present invention will be described in detail. Aggregated particles 92 of magnesium oxide (MgO) have been confirmed by experiments of the present inventor mainly to suppress the “discharge delay” in the write discharge and to improve the temperature dependence of the “discharge delay”. . Therefore, in the embodiment of the present invention, the aggregated particles 92 are arranged as an initial electron supply unit required at the time of rising of the discharge pulse by utilizing the property that the advanced initial electron emission characteristics are superior to the base film 91.

  The “discharge delay” is considered to be mainly caused by a shortage of the amount of initial electrons that are triggered from the surface of the base film 91 being discharged 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 aggregated particles 92 of magnesium oxide (MgO) are dispersedly arranged on the surface of the base film 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 base film 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.

  As described above, the PDP 1 according to the embodiment of the present invention includes the base film 91 that achieves both low-voltage driving and charge retention, and the magnesium oxide (MgO) aggregated particles 92 that have the effect of preventing discharge delay. Thus, as a whole PDP 1, high-definition PDP can be driven at high speed with a low voltage, and high-quality image display performance with suppressed lighting failure can be realized.

  In the embodiment of the present invention, the aggregated particles 92, in which several crystal particles 92a are aggregated, are discretely dispersed on the base film 91, and a plurality of particles are adhered so as to be distributed almost uniformly over the entire surface. is doing. FIG. 6 is an enlarged view for explaining the agglomerated particles 92.

  Aggregated particles 92 are those in which crystal particles 92a having a predetermined primary particle size are aggregated or necked, as shown in FIG. 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. The particle size of the agglomerated particles 92 is about 1 μm, and the crystal particles 92a preferably have a polyhedral shape having seven or more surfaces 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 an MgO precursor such as magnesium carbonate or magnesium hydroxide is calcined and produced, the particle size can be controlled by controlling the calcining temperature and the calcining atmosphere. Generally, the firing temperature can be selected in the range of 700 ° C. to 1500 ° C., but 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. is there. Furthermore, by obtaining the crystal particles 92a by heating the MgO precursor, a plurality of primary particles are bonded to each other by a phenomenon called agglomeration or necking in the production process, whereby the agglomerated particles 92 can be obtained.

  FIG. 7 shows the discharge delay in the protective layer 9 in the case of using the base film 91 made of a metal oxide of magnesium oxide (MgO) and calcium oxide (CaO) in the PDP in the embodiment of the present invention. It is a figure which shows the relationship with a calcium (Ca) density | concentration. The base film 91 is composed of a metal oxide composed of magnesium oxide (MgO) and calcium oxide (CaO), and the metal oxide has a magnesium oxide (MgO) peak in the X-ray diffraction analysis on the surface of the base film 91. A peak exists between the diffraction angle at which the peak is generated and the diffraction angle at which the peak of calcium oxide (CaO) is generated. FIG. 7 shows the case where only the base film 91 is used as the protective layer 9 and the case where the aggregated particles 92 are arranged on the base film 91, and the discharge delay is caused by calcium (Ca) contained in the base film 91. The case where it is not done is shown as a standard.

  Further, the electron emission performance is a numerical value indicating that the larger the electron emission performance, the greater the amount of electron emission, and is expressed by the initial electron emission amount determined by the surface state, the gas type and the state. The initial electron emission amount can be measured by a method of measuring the amount of electron current emitted from the surface by irradiating the surface with ions or an electron beam. However, the evaluation of the surface of the front plate 2 of the PDP 1 can be performed nondestructively. With difficulty. Therefore, the method described in JP 2007-48733 A was used. That is, among the delay times at the time of discharge, a numerical value called a statistical delay time, which is a measure of the likelihood of occurrence of discharge, is measured, and when the reciprocal is integrated, a numerical value corresponding to the initial electron emission amount is obtained.

  Therefore, this numerical value is used for evaluation. The delay time at the time of discharge means the time of discharge delay when the discharge is delayed from the rising edge of the pulse, and the discharge delay is the time when the initial electrons that trigger when the discharge is started are discharged from the surface of the protective layer 9 to the discharge space. It is considered as a main factor that it is difficult to be released into the inside.

  As is apparent from FIG. 7, in the case of only the base film 91 and in the case where the aggregated particles 92 are arranged on the base film 91, the discharge delay increases as the calcium (Ca) concentration increases in the case of the base film 91 alone. On the other hand, it can be seen that by disposing the agglomerated particles 92 on the base film 91, the discharge delay can be significantly reduced, and the discharge delay hardly increases even when the calcium (Ca) concentration is increased.

  Next, the results of experiments conducted to confirm the effect of the protective layer 9 having the aggregated particles 92 in the embodiment of the present invention will be described. First, a PDP having a base film 91 having a different structure and agglomerated particles 92 provided on the base film 91 was made as a prototype. Prototype 1 is a PDP in which a protective layer 9 made only of a magnesium oxide (MgO) base film 91 is formed. Prototype 2 is a protective layer 9 made only of a base film 91 in which magnesium oxide (MgO) is doped with impurities such as Al and Si. Prototype 3 is a PDP in which a protective layer 9 is formed by spraying and adhering only primary particles of magnesium oxide (MgO) crystal particles 92a on a base film 91 made of magnesium oxide (MgO).

  On the other hand, the prototype 4 is the PDP in the embodiment of the present invention, and the above-described sample A is used as the protective layer 9. That is, the protective layer 9 includes a base film 91 made of a metal oxide of magnesium oxide (MgO) and calcium oxide (CaO), and aggregated particles 92 obtained by aggregating crystal particles 92a on the base film 91 over the entire surface. So that they are distributed almost uniformly. In the X-ray diffraction analysis of the surface of the base film 91, the base film 91 is set so that a peak exists between the minimum diffraction angle and the maximum diffraction angle of a peak generated from a single oxide constituting the base film 91. ing. That is, the minimum diffraction angle in this case is 32.2 degrees for calcium oxide (CaO), the maximum diffraction angle is 36.9 degrees for magnesium oxide (MgO), and the peak of the diffraction angle of the base film 91 is 36.1 degrees. To exist.

  The electron emission performance and charge retention performance of these PDPs were examined, and the results are shown in FIG. The electron emission performance is evaluated by the above-described method, and the charge retention performance is measured by using a voltage (hereinafter referred to as Vscn lighting voltage) applied to the scan electrode necessary for suppressing the charge emission phenomenon when the PDP is manufactured. ) Voltage value was used. That is, a lower Vscn lighting voltage indicates a higher charge holding capability. This makes it possible to use components having a low withstand voltage and a small capacity as the power source and each electrical component in designing the PDP. In the current product, an element having a withstand voltage of about 150 V is used as a semiconductor switching element such as a MOSFET for sequentially applying a scanning voltage to the panel, and the Vscn lighting voltage is 120 V or less in consideration of variation due to temperature. It is desirable to keep it at a minimum.

  FIG. 8 is a diagram showing the results of examining the electron emission performance and the charge retention performance of the PDP in the embodiment of the present invention. As is clear from FIG. 8, the aggregated particles 92 obtained by aggregating the single crystal particles 92a of magnesium oxide (MgO) were sprayed on the base film 91 in the embodiment of the present invention and distributed uniformly over the entire surface. In the evaluation of the charge retention performance, the work 4 can make the Vscn lighting voltage 120 V or less, and the electron emission performance is much better than the prototype 1 in the case of the protective layer made only of magnesium oxide (MgO). Characteristics can be obtained.

  In general, the electron emission capability and the charge retention capability of the protective layer of the PDP are contradictory. For example, it is possible to improve the electron emission performance by changing the film forming conditions of the protective layer, or by forming a film by doping impurities such as Al, Si, and Ba in the protective layer. The Vscn lighting voltage also increases.

  In the PDP of the prototype 4 in which the protective layer 9 is formed in the embodiment of the present invention, the electron emission capability is 8 times or more compared to the prototype 1 using the protective layer only of magnesium oxide (MgO). The charge holding ability can be obtained with a Vscn lighting voltage of 120 V or less. Therefore, it is useful for PDPs with a large number of scanning lines and a small cell size due to high definition, satisfying both electron emission capability and charge retention capability, and reducing discharge delay and good image display Can be realized.

  Next, the particle size of the crystal particles used in the protective layer 9 of the PDP according to the present invention will be described in detail. In the following description, the particle diameter means an average particle diameter, and the average particle diameter means a volume cumulative average diameter (D50).

  FIG. 9 shows the experimental results of examining the electron emission performance of the prototype 4 of the present invention described with reference to FIG. 8 by changing the particle size of the crystal particles 92a. In FIG. 9, the particle diameter of the crystal particle 92 a was measured by observing the crystal particle 92 a with an SEM. As shown in FIG. 9, it can be seen that when the particle size is reduced to about 0.3 μm, the electron emission performance is lowered, and when it is approximately 0.9 μm or more, high electron emission performance is obtained.

  Incidentally, in order to increase the number of electrons emitted in the discharge cell, it is desirable that the number of crystal particles 92a per unit area on the base film 91 is large. The crystal particles 92 a are present in the portion corresponding to the top of the partition wall 14 of the back plate 10 that is in close contact with the protective layer 9 of the second layer, so that the top of the partition wall 14 is damaged and the material rides on the phosphor 15. It has been found that a phenomenon occurs in which the corresponding cell does not normally turn on and off. The phenomenon of the partition wall breakage is unlikely to occur unless the crystal particle 92a is present at the portion corresponding to the top of the partition wall 14. Therefore, the probability of the breakage of the partition wall 14 increases as the number of crystal particles 92a attached increases. From this point of view, when the crystal particle diameter is increased to about 2.5 μm, the probability of partition wall breakage increases rapidly, and when the crystal particle diameter is smaller than 2.5 μm, the probability of partition wall breakage is kept relatively small. be able to.

  From the above results, in the PDP according to the embodiment of the present invention, if the aggregated particles 92 having a particle size in the range of 0.9 μm to 2 μm are used as the aggregated particles 92, the above-described effects of the present invention can be stably achieved. It turned out to be obtained. In addition, although it demonstrated using the magnesium oxide (MgO) particle | grains as a crystal particle, metal oxides, such as Sr, Ca, Ba, Al, etc. which have high electron emission performance similarly to magnesium oxide (MgO) also in this other single crystal particle. Since the same effect can be obtained even if crystal grains made of a material are used, the particle type is not limited to magnesium oxide (MgO).

  By the way, in the present invention, when the protective layer 9 is formed of a metal oxide selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide having the characteristics as described above, the discharge start voltage of the panel is reduced, Although the discharge delay can be reduced and the discharge can be stabilized, these materials are highly reactive with impurity gases such as water and carbon dioxide, and the discharge characteristics are particularly deteriorated by reacting with water and carbon dioxide. This tends to cause variations in the discharge characteristics of each discharge cell.

  Therefore, in the present invention, in the sealing step of the manufacturing process shown in FIG. 3, the inside of the discharge space 16 is in a positive pressure state through a through hole opened in the discharge space 16 provided in the back plate 10 as the second substrate. In this manner, the reaction between the protective layer and the impurity gas during the panel manufacturing process is suppressed by flowing the dry gas.

  In addition, the dry gas has an effect of discharging the impure gas desorbed from the surface of the protective layer to the outside of the panel. However, in some cases, the first substrate and the second substrate are deformed by the flow of the dry gas, The discharge space between the two substrates may swell. The swelling of the discharge space during the sealing and discharging process causes unevenness in the flow of dry gas, resulting in unevenness in the impure gas adsorbed on the surface of the protective layer, which causes uneven drive voltage and uneven display brightness. Will be generated.

  Therefore, in the present invention, in the sealing step, the holding step of flowing the dry gas into the discharge space and holding the inside of the discharge space in a positive pressure state, and after this holding step, increasing the inflow amount of the dry gas, By providing a discharge process for discharging the gas in the discharge space, occurrence of display unevenness during image display is suppressed.

  Hereinafter, the manufacturing method of this invention is demonstrated using FIGS.

  FIG. 10 is a diagram showing an example of a temperature profile in the sealing process and the exhaust process used in the embodiment of the present invention.

  The details of the profile of the sealing process, the subsequent exhaust process, and the discharge gas supply process will be described later in order, but for convenience of explanation, the sealing process, the subsequent exhaust process, and the discharge gas supply process are performed at the same temperature. In view of the above, it is divided into the following four periods. That is, a period for raising from the room temperature to the softening point (period 1), a period for raising from the softening point to the sealing temperature, holding for a certain time, and then lowering to the softening point (period 2) (above, sealing process), softening These are a period in which the temperature is maintained at a temperature near or slightly lower than the point temperature and then lowered to room temperature (period 3: exhaust process), and a period after the temperature is lowered to room temperature (period 4: discharge gas supply process).

  Here, the softening point refers to a temperature at which the glass frit softens, and the softening point temperature of the glass frit in the present embodiment is about 420 ° C., for example. Further, the sealing temperature is a temperature at which the front plate 2 and the back plate 10 are sealed by a frit that is a sealing member, and the sealing temperature in the present embodiment is, for example, about 490 ° C. .

  FIG. 11 is an enlarged view of the sealing step (periods 1 and 2) in FIG.

  In the period 1 of the sealing step, a holding step of flowing dry gas into the discharge space to hold the discharge space in a positive pressure state, and after this holding step, increasing the amount of inflow of dry gas and the discharge And a discharge process for discharging the gas in the space. Furthermore, since the atmosphere in the discharge space after the alignment is air, a gas replacement step for quickly replacing the discharge space with the dry gas may be provided in some cases. The gas replacement step is desirable because it can quickly replace the dry gas in the discharge space by increasing the inflow amount of the dry gas as compared with the holding step, so that the processing time of the sealing step can be shortened.

  FIG. 12 is a diagram schematically showing a method for manufacturing a panel according to an embodiment of the present invention. FIGS. 12A to 12D show the gas inside the panel in the above-described period 1 to period 4, respectively. It is a figure which shows the flow. In FIG. 12, 21 is a glass frit which is a sealing member applied to the periphery of the back plate 10, 22 is a through hole provided in the back glass substrate 11 of the back plate 10, and this through hole 22 is a discharge space. The rear glass substrate 11 is provided so as to open to 16. 23 to 25 are valves, and 26 is a gas relief valve.

  First, after the front plate 2 and the back plate 10 are positioned and overlapped so that the display electrode 6 and the address electrode 12 are orthogonally opposed to each other, the valve 23 is opened as shown in FIG. The heater is turned on while flowing the dry gas from the through hole 22 into the panel, and the temperature inside the heating furnace is raised to the softening point temperature of the glass frit 21 for sealing.

  At this time, as shown by the symbol A, the dry gas that has flowed into the panel flows into the outside of the panel through the gap between the front plate 2 and the glass frit 21 formed on the back plate 10. ing. In the present embodiment, a dry nitrogen gas having a dew point of −45 ° C. or lower is used as the dry gas, and the flow rate is about 0.1 L / min in the holding process and about 1 L / min in the discharge process. Further, when the panel temperature reaches about 350 ° C., the holding process is shifted to the discharging process. The setting of the transition temperature to the discharge process will be described later.

  In the discharge process, it is desirable to flow the dry gas so that the front plate 2 and the back plate 10 are not deformed from the viewpoint of preventing display unevenness. As a method for suppressing deformation, a method of adjusting the flow rate of the dry gas, a method of mechanically pressing the substrate, and the like can be considered. (Period 1).

  Next, when the temperature inside the heating furnace becomes equal to or higher than the softening point temperature of the glass frit 21, as shown in FIG. 12 (b), the gas relief valve 26 is opened and the pressure inside the panel is changed to the sealing furnace. The positive pressure should be slightly higher than the internal pressure. Then, the temperature inside the heating furnace is raised to the sealing temperature, and the temperature inside the heating furnace is maintained at a temperature equal to or higher than the sealing temperature for a certain time (here, 30 minutes). During this time, the molten glass frit 21 slightly flows, and the front plate 2 and the back plate 10 are sealed.

  Thereafter, the heater is turned off and the temperature of the heating furnace is lowered to a temperature equal to or lower than the softening point (period 2).

  The exhaust process is a process of exhausting the gas inside the panel. When the temperature inside the heating furnace becomes equal to or lower than the softening point temperature, as shown in FIG. 12C, the valve 23 is closed, the valve 24 is opened, and the inside of the panel is exhausted from the through hole 22 through the glass tube. Then, the exhaust is continuously performed while maintaining the temperature inside the heating furnace for a predetermined time by controlling the heater.

  Thereafter, the heater is turned off and the temperature inside the heating furnace is lowered to room temperature. During this time, exhaustion is continued (period 3).

  The discharge gas supply step is a step of supplying a discharge gas mainly containing Ne and Xe into the evacuated panel. After the temperature inside the heating furnace has dropped to room temperature, as shown in FIG. 12D, the valve 24 is closed, the valve 25 is opened, and the discharge gas is supplied through the through-hole 22 to a predetermined pressure.

In the present embodiment, the discharge gas is, for example, a mixed gas of Xe: 10% and Ne: 90%, and the predetermined atmospheric pressure is 6 × 10 ⁴ Pa. However, the discharge gas is not limited to this, and may be, for example, a gas of Xe: 100%.

  Thereafter, the glass tube connected to the through hole 22 is heat-sealed (period 4).

  As described above, the front plate 2 and the back plate 10 are bonded together, and a panel filled with the discharge gas therebetween is completed.

  In addition, about the transfer conditions from the holding | maintenance process in the period 1 of a sealing process to a discharge process, it thinks as follows. The cause of display luminance unevenness during image display has been found by the inventors to be due to uneven discharge voltage due to uneven adsorption of impure gas (especially water) to the protective layer. Impurity irregularity (moisture) adsorption unevenness depends on the flow of dry gas, and the amount of water adsorbed on the protective layer changes depending on the flow of dry gas. It becomes a factor to produce. The flow distribution of the dry gas in the panel surface is remarkably generated when the inside of the panel is expanded by the inflow of the dry gas into the panel. For this reason, it can be improved by suppressing the swelling (deformation) of the panel. However, this is also related to the amount of water adsorbed on the protective layer. It was found that the flow distribution does not affect so much.

  An example of the desorption temperature profile of water from the protective layer is shown in FIG. FIG. 13 is a desorption temperature profile of water (mass number 18) measured by the TDS method. As shown in FIG. 13, water is desorbed from a temperature of about 250 ° C., reaches a desorption peak at a temperature of about 350 ° C., and decreases at a temperature higher than that. That is, since water is almost desorbed from the protective layer at about 350 ° C., it can be seen that if the temperature is higher than that, the degree of desorption is less affected by the flow of the dry gas. For this reason, it becomes possible to clean the inside of the panel substantially uniformly by discharging the water desorbed into the space to the outside of the panel.

  In order to confirm the effect of the manufacturing method of the present invention, the inventors produced prototype 5 from prototype 1 under the conditions shown in Table 1. In Table 1, the temperature T1 is a temperature at which the holding process in FIG.

  As shown in Table 1, Prototype 1 and Prototype 2 are comparative examples for the present invention, and both T1 was 350 ° C. In the prototype 1, the drying gas flow rate in the holding process and the discharging process is the same, and in the prototype 2, the drying gas flow rate in the holding process is made larger than that in the discharging process. In both cases, the display uniformity was poor. This is thought to be due to the distribution of the desorption amount in the desorption characteristics of FIG. 13 because the dry gas flow rate is large in the temperature range where water is mainly desorbed.

  On the other hand, in the prototypes 3 to 5, the flow rate of the dry gas in the discharge process is larger than that in the holding process. In the temperature range where the water begins to desorb, the distribution of the desorption amount is suppressed by reducing the flow rate of the dry gas, and the impure gas desorbed into the space in the subsequent discharge process is discharged out of the panel. For this reason, a display with high display uniformity and good display performance is obtained.

  Further, in the prototypes 3 to 5, the temperature of T1 is changed. However, by making the temperature of T1 higher than the desorption peak temperature of water from the protective layer (in FIG. 13, 350 ° C. or higher), Products with high display uniformity are obtained (Prototype 4 and Prototype 5).

  In the holding step, the flow rate of the dry gas is reduced to such an extent that the panel is not deformed in order to suppress the distribution of the desorption amount from the protective layer. For this reason, it is considered that the ability to discharge the desorbed impure gas outside the panel is insufficient, and therefore it is necessary to sufficiently increase the flow rate of the dry gas in the subsequent discharge process.

  In the holding step, it is not necessary to positively flow the dry gas into the panel, and it may be held at a positive pressure so as to prevent air from entering. Therefore, for example, as shown in FIG. 12B, the gas relief valve 26 may be opened while supplying the dry gas.

  As described above, in the present embodiment, in the sealing step, the dry gas is caused to flow into the discharge space 16 through the through-hole 22 opened in the discharge space 16 provided in the back plate 10 and the inside of the discharge space. Since there is a holding step for holding in a positive pressure state and a discharge step for increasing the inflow of dry gas and discharging the gas in the discharge space after this holding step, the discharge of the discharge cells locally in the panel Since variations in discharge characteristics among discharge cells can be suppressed without deterioration of characteristics, a panel having excellent discharge characteristics and high display uniformity can be manufactured.

  In the present embodiment, the front plate 2 and the back plate 10 are deformed in the holding step in the period 1 of the sealing step so that the discharge space does not bulge. This is desirable for improving display uniformity.

  Note that the fact that the front plate 2 or the back plate 10 in the present invention is not deformed does not mean that the front plate 2 or the rear plate 10 is not deformed at all, and according to the experiments by the present inventors, the thickness direction of the substrate before and after the inflow of the dry gas. It was confirmed that the displacement should be 50 microns or less, which is a measurement error. That is, it is sufficient if the displacement in the thickness direction of the substrate before and after the inflow of the dry gas is 50 microns or less, which is a measurement error.

  In the embodiment of the present invention, the substrate is not deformed by the flow rate of the dry gas. However, the present invention is not limited to this method. For example, the deformation may be suppressed by pressing with a jig.

  In the embodiment of the present invention, dry nitrogen gas is used as the dry gas, but the present invention is not limited to this. The use of a gas that does not contain oxygen as a dry gas is desirable for preventing residual organic components in the panel from burning and carbonizing the protective layer. Examples of the dry gas include not only nitrogen gas but also rare gases such as helium gas, neon gas, argon gas, krypton gas, and xenon gas.

  As described above, the present invention is useful in realizing a PDP having high image quality display performance and low power consumption.

The perspective view which shows the structure of PDP in embodiment of this invention Sectional drawing which shows the structure of the front plate of the PDP Flow chart showing the manufacturing method of the panel The figure which shows the X-ray-diffraction result in the base film of the PDP The figure which shows the X-ray-diffraction result in the base film of the other structure of the PDP Enlarged view for explaining the aggregated particles of the PDP The figure which shows the relationship between the discharge delay of the same PDP, and the calcium (Ca) density | concentration in a protective layer The figure which shows the result of having investigated about the electron emission performance and charge retention performance of the PDP Characteristic diagram showing the relationship between the particle size of crystal grains used in the PDP and the electron emission characteristics The figure which shows an example of the temperature profile of the heating furnace for sealing and exhaust The figure which shows an example of the temperature profile of the heating furnace for sealing and exhaust Explanatory drawing which shows the manufacturing method of this invention typically The figure which shows the desorption temperature profile of the water from the protective film in this invention

1 PDP
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 (light shielding layer)
DESCRIPTION OF SYMBOLS 8 Dielectric layer 9 Protective layer 10 Back plate 11 Back glass substrate 12 Address electrode 13 Base dielectric layer 14 Partition 15 Phosphor layer 16 Discharge space 21 Glass frit 22 Through-hole 81 First dielectric layer 82 Second dielectric layer 91 Base film 92 Agglomerated particles 92a Crystal particles

Claims (5)

A dielectric layer is formed so as to cover the display electrode formed on the substrate, and a first substrate having a protective layer formed on the dielectric layer, and a discharge space filled with a discharge gas in the first substrate are formed. And a second substrate having an address electrode formed in a direction intersecting with the display electrode of the first substrate and provided with a partition wall for partitioning the discharge space, and the first substrate and the first substrate A plasma display panel manufacturing method comprising a sealing step in which two substrates are arranged opposite to each other and a peripheral portion is sealed with a sealing member, wherein the protective layer of the first substrate is made of magnesium oxide, calcium oxide, oxidized The sealing step is performed by injecting a dry gas into the discharge space through a through-hole that opens into the discharge space, and is formed of a metal oxide selected from strontium and barium oxide. A plasma display panel comprising: a holding step for holding the inside of the discharge space in a positive pressure state; and a discharge step for increasing the inflow of dry gas after the holding step and discharging the gas in the discharge space. Manufacturing method. 2. The method of manufacturing a plasma display panel according to claim 1, wherein the discharging step of the sealing step is performed below a softening point of the sealing member. 2. The method of manufacturing a plasma display panel according to claim 1, wherein the discharging step of the sealing step is performed at a temperature higher than a desorption peak temperature of water from the protective layer. 2. The method of manufacturing a plasma display panel according to claim 1, wherein the sealing step is performed so that the first substrate and the second substrate are not deformed below a softening point of the sealing member. The protective layer is formed of a metal oxide composed of at least two oxides selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide, and the metal oxide has a specific orientation plane in X-ray diffraction analysis. 2. The plasma display panel according to claim 1, wherein a peak exists between a minimum diffraction angle and a maximum diffraction angle generated from a single oxide constituting the metal oxide. Method.

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