WO2011102145A1

WO2011102145A1 - Production method for plasma display panel

Info

Publication number: WO2011102145A1
Application number: PCT/JP2011/000939
Authority: WO
Inventors: 後藤　真志; 土居　由佳子
Original assignee: パナソニック株式会社
Priority date: 2010-02-22
Filing date: 2011-02-21
Publication date: 2011-08-25
Also published as: JP2011171199A

Abstract

Disclosed is a production method for plasma display panels involving a sealing step for arranging a front plate (2) and a back plate (10) in a facing manner and sealing the periphery thereof with a sealing member, wherein the protective layer (9) of the front plate (2) is formed from a metal oxide comprising at least two or more oxides selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide. The method involves a step for low-pressure heating the protective layer (9) prior to the sealing step, and the metal oxide, in X-ray diffraction analysis, has a peak that occurs between a minimum angle of diffraction and a maximum angle of diffraction generated by the simple oxide substances forming the metal oxide on a surface with a specified orientation.

Description

Method for manufacturing plasma display panel

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

Plasma display panels (hereinafter referred to as PDPs) are capable of realizing high definition and large screens, so 100-inch class televisions have 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.

The PDP is basically composed of 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 a discharge gas of neon (Ne) -xenon (Xe) is 400 Torr to 600 Torr (5.3 ×) in a discharge space partitioned by a partition wall. 10 ⁴ Pa to 8.0 × 10 ⁴ Pa). 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.).

In recent years, the definition of television has been increased, and the market demands a full HD (high definition) (1920 × 1080 pixels: progressive display) PDP with low cost, low power consumption, and high brightness. 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.

JP 2002-260535 A Japanese Patent Laid-Open No. 11-339665 JP 2006-59779 A JP-A-8-236028 JP-A-10-334809

The PDP of the present invention includes a first substrate in which a dielectric layer is formed so as to cover a display electrode formed on the substrate and a protective layer is formed on the dielectric layer, and a discharge in which the first substrate is filled with a discharge gas. And a second substrate which is disposed so as to be opposed to each other and forms an address electrode in a direction intersecting with the display electrode of the first substrate and which has a partition wall which partitions the discharge space. A method for manufacturing a plasma display panel comprising a sealing step in which a substrate is disposed oppositely and a peripheral portion is sealed with a sealing member, wherein the protective layer of the first substrate includes magnesium oxide, calcium oxide, strontium oxide, and It is formed of a metal oxide composed of at least two oxides selected from barium oxide, and the metal oxide is a simple substance of an oxide constituting a metal oxide having a specific orientation plane in X-ray diffraction analysis. Is intended to present a peak between the minimum diffraction angle and a maximum diffraction angle of more generated, and the protective layer has a heating step in the reduced pressure atmosphere prior to the sealing step.

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.

FIG. 1 is a perspective view showing a structure of a PDP according to an embodiment. FIG. 2 is a cross-sectional view showing the configuration of the front plate of the PDP. FIG. 3 is a flowchart showing a method for manufacturing the panel. FIG. 4 is a diagram showing an X-ray diffraction result in the base film of the PDP. FIG. 5 is a diagram showing an X-ray diffraction result in the base film having another configuration of the PDP. FIG. 6 is an enlarged view for explaining the aggregated particles of the PDP. FIG. 7 is a diagram showing the relationship between the discharge delay of the PDP and the calcium (Ca) concentration in the protective layer. FIG. 8 is a diagram showing the results of examining the electron emission performance and the lighting voltage of the PDP. FIG. 9 is a characteristic diagram showing the relationship between the particle size of the crystal particles used in the PDP and the electron emission performance.

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

FIG. 1 is a perspective view showing a structure of a PDP in one embodiment. The basic structure of the PDP 1 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 such as Xe and Ne at a pressure of 400 Torr to 600 Torr (5.3 × 10 ⁴ Pa to 8.0 × 10 ⁴ Pa).

On the front glass substrate 3 of the front plate 2, a pair of strip-shaped display electrodes 6 each composed of a scanning electrode 4 and a sustain electrode 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 16 is formed at a position where the scan electrode 4 and the sustain electrode 5 and the address electrode 12 intersect, and the discharge space 16 having the red, green, and blue phosphor layers 15 arranged in the direction of the display electrode 6 is used for color display. It becomes a pixel for.

FIG. 2 is a cross-sectional view showing a detailed configuration of the front plate of the PDP according to one embodiment. 2 is shown upside down from FIG. As shown in FIG. 2, a display electrode 6 and a light shielding layer 7 including scanning electrodes 4 and sustain 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 made of

transparent electrodes

4a and 5a made of indium tin oxide (ITO), tin oxide (SnO ₂ ), and the like, 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 1 was created by a front plate creating process and a back plate creating process, a reduced pressure heating process in which the front plate 2 created by the front plate creating process is heated in a vacuum atmosphere, and a back plate creating process. A frit coating step of applying a glass frit as a sealing member outside the image display area of the back plate 10 and then pre-baking at a temperature of about 350 ° C. to remove a resin component of the glass frit and a reduced pressure heating step A sealing process in which the finished front plate 2 and the back plate 10 in which the frit application process is finished are pasted and sealed, an exhausting process in which the gas in the discharge space 16 is exhausted thereafter, and the interior of the panel that has been evacuated thereafter And a discharge gas supply step for supplying a discharge gas mainly composed of Ne and Xe. A panel is completed through these steps.

Here, the sealing member is preferably a frit mainly composed of bismuth oxide or vanadium oxide. Examples of the frit mainly composed of bismuth oxide include 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. Further, 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 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 (dielectric material) layer is formed by applying a dielectric paste on the front glass substrate 3 by a die coating method or the like so as to cover the scanning electrode 4, the sustain electrode 5 and the light shielding layer 7. 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 present embodiment, the base film 91 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 formed by things.

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, 1 Pa is considered as the upper limit of the pressure that can actually be taken in the sputtering method and 0.1 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 ), 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 impurity elements such as alkali metals, B, Si, Fe, and Al, unnecessary interparticle adhesion and sintering occur during heat treatment, and highly crystalline magnesium oxide ( This is because it is difficult to obtain MgO) crystal particles 92a. 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 dispersed and dispersed on the surface of the base film 91 by spraying, screen printing, electrostatic coating, or the like. Let 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.

By 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 to complete front plate 2.

On the other hand, in the back plate making 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 barrier rib forming paste containing barrier rib material is applied on the underlying dielectric layer 13 and patterned into a predetermined shape to form a barrier rib 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. That is, 20% by weight to 40% by weight of bismuth oxide (Bi ₂ O ₃ ), 0.5% by weight to 12% of at least one selected from calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO). Contains 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 place 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%.

In addition to the above components, zinc oxide (ZnO) is contained in an amount of 0 to 40% by weight, boron oxide (B ₂ O ₃ ) in an amount of 0 to 35% by weight, and silicon oxide (SiO ₂ ) in an amount of 0 to 4% by weight. 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 prepared by pulverizing a dielectric material composed of these composition components with a wet jet mill or a ball mill so that the particle diameter becomes 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 baking 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%. It contains ˜21 wt%, and contains 0.1 wt% ˜7 wt% of at least one selected from molybdenum oxide (MoO ₃ ), tungsten oxide (WO ₃ ), and cerium oxide (CeO ₂ ).

In place 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%.

A dielectric material powder is prepared by pulverizing a dielectric material composed of these composition components with a wet jet mill or a ball mill so that the particle diameter becomes 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 form 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. Thereafter, 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 has a bismuth oxide (Bi ₂ O ₃ ) content of the second dielectric layer 82 in order to suppress the reaction of the

metal bus electrodes

4b and 5b with silver (Ag). More than the content of (Bi ₂ O ₃ ), the content 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 wt% 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.

Also, as the thickness of the dielectric layer 8 is smaller, the effect of improving the luminance and reducing the discharge voltage becomes more prominent. Therefore, it is desirable to set the thickness as small as possible within the range where the withstand voltage does not decrease. From this point of view, 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.

In the PDP 1 manufactured in this way, even when a silver (Ag) material is used for the display electrode 6, the front glass substrate 3 has little coloring phenomenon (yellowing), and bubbles are generated in the dielectric layer 8. Thus, the dielectric layer 8 having excellent withstand voltage performance can be realized.

Next, details of the protective layer 9 in the present embodiment will be described. In the PDP 1 according to the present embodiment, 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 92 a deposited on the base film 91. A plurality of aggregated particles 92 are formed. 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 of the PDP in one embodiment. 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.

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 (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 (BaO) alone has a peak at a diffraction angle of 27.9 degrees.

In PDP 1 in the present embodiment, at least two or more oxides selected from magnesium oxide (MgO), calcium oxide (CaO), strontium oxide (SrO), and barium oxide (BaO) are used as base film 91 of protective layer 9. It is made of a metal oxide made of a material.

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 barium oxide. The results when (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, the base film 91 of the PDP 1 according to the present embodiment has a specific orientation in the X-ray diffraction analysis of the surface of the base film 91 of the metal oxide constituting the base film 91, whether it is a single component or two components. A peak exists between the minimum diffraction angle and the maximum diffraction angle of a peak generated from a single oxide constituting the surface metal oxide.

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 described above even when other crystal orientation planes are 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 in the present embodiment is configured such that a peak exists between the minimum diffraction angle and the maximum diffraction angle of the peak generated from a single oxide constituting the metal oxide. Yes. 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 compared to 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 PDP1.

Here, in the PDP 1 in the present embodiment, the discharge sustaining voltage of the PDP 1 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 1 in 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 compared to 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 1 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. The structure of the material reduces the reactivity, and is formed with a crystal structure with few impurities and oxygen vacancies. Therefore, it is possible to suppress excessive emission of electrons when the PDP 1 is driven. 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 formed on the base film 91 in the present embodiment and agglomerated a plurality of magnesium oxide (MgO) crystal particles 92a 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 present embodiment includes the base film 91 that achieves both the low voltage driving and the charge retention effect, 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 1 can be driven at a high speed with a low voltage, and high-quality image display performance with reduced lighting defects can be realized.

In the present embodiment, 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. Yes. FIG. 6 is an enlarged view for explaining the agglomerated particles 92.

The agglomerated 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.

Further, 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 is a diagram showing the relationship between the discharge delay of the PDP and the calcium (Ca) concentration in the protective layer in one embodiment. Specifically, among the PDP 1, the discharge delay and the calcium (Ca) concentration in the protective layer 9 when using the base film 91 composed of a metal oxide of magnesium oxide (MgO) and calcium oxide (CaO) Shows the relationship. 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.

Also, the electron emission performance is a numerical value indicating that the larger the electron emission performance is, the more electron emission performance is expressed by the initial electron emission amount determined by the surface state, the gas type and its 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. 16 is considered to be a major factor that is difficult to release.

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 present embodiment will be described. First, a PDP 1 having a base film 91 having a different configuration and aggregated particles 92 provided on the base film 91 was made as a prototype. Prototype 1 is a PDP 1 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 impurities such as Al and Si are doped in magnesium oxide (MgO). The prototype 3 is a PDP 1 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 1 in the present embodiment, 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 it is 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.

These PDPs 1 were examined for their electron emission performance and charge retention performance, 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 the voltage applied to the scan electrode 4 (hereinafter referred to as Vscn lighting voltage) necessary for suppressing the charge emission phenomenon when the PDP 1 is manufactured. Voltage value) was used. That is, a lower Vscn lighting voltage indicates a higher charge retention 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 when designing the PDP 1. 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 lighting voltage of the PDP in one embodiment. As is apparent from FIG. 8, prototype 4 in which aggregated particles 92 obtained by aggregating single crystal particles 92a of magnesium oxide (MgO) are dispersed on base film 91 in the present embodiment and uniformly distributed over the entire surface. In the evaluation of the charge retention performance, the Vscn lighting voltage can be reduced to 120 V or less, and the electron emission performance is much better than that of the prototype 1 in the case of a protective layer made only of magnesium oxide (MgO). Obtainable.

In general, the electron emission capability and the charge retention capability of the protective layer of PDP 1 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 1 of the prototype 4 in which the protective layer 9 is formed in the present embodiment, the electron emission capability is more than eight times that of the prototype 1 using the protective layer of only magnesium oxide (MgO). As the charge retention capability, a Vscn lighting voltage of 120 V or less can be obtained. Therefore, it is useful for the PDP1 with the increased number of scanning lines and the small cell size due to the high definition, satisfying both the electron emission ability and the charge retention ability, and reducing the discharge delay and good image display. Can be realized.

Next, the particle size of the crystal particles 92a used for the protective layer 9 of the PDP 1 in the present embodiment 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 is a characteristic diagram showing the relationship between the particle size of the crystal particles used in the PDP and the electron emission performance in one embodiment. Specifically, the experimental results of examining the electron emission performance by changing the particle size of the crystal particles 92a in the prototype 4 in the present embodiment described with reference to FIG. 8 are shown. 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. 8, 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.

By the way, in order to increase the number of emitted electrons in the discharge cell, it is desirable that the number of crystal particles 92a per unit area on the base film 91 is larger. However, according to experiments, the protective layer 9 of the front plate 2 is observed. The crystal particles 92a 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 substrate, and the top of the partition wall 14 is damaged, and the material is placed on the phosphor layer 15. It has been found that a phenomenon occurs in which a cell that is normally turned on and off does not occur. The phenomenon of the partition wall breakage is unlikely to occur unless the crystal particles 92a are present at the portion corresponding to the top of the partition wall 14, and therefore, the probability of breakage of the partition wall 14 increases as the number of attached crystal particles 92a 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 1 according to the present embodiment, 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 obtained. I found out that 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. The same effect can be obtained even when crystal grains made of a material are used. The particle type is not limited to magnesium oxide (MgO).

By the way, in this embodiment, when the protective layer 9 is formed of a metal oxide selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide having the above-described characteristics, the discharge start voltage of the panel is lowered. Therefore, the discharge delay can be reduced and the discharge can be stabilized. However, these materials are highly reactive with impurity gases such as water and carbon dioxide, and in particular, the discharge characteristics are likely to deteriorate due to reaction with water and carbon dioxide, resulting in variations in the discharge characteristics of each discharge cell. Cheap.

Therefore, in the present embodiment, the front plate 2 is heated under reduced pressure before the sealing step of the manufacturing process shown in FIG. Hereinafter, the reduced pressure heating process in the present embodiment will be described in detail.

In the reduced pressure heating step, the front plate 2 created in the front plate creation step is introduced into a vacuum apparatus connected to an exhaust pump, and after the pressure is reduced to a predetermined pressure, heat treatment is performed. In the present embodiment, after the front plate 2 is introduced into the vacuum apparatus, the pressure is reduced until the degree of vacuum becomes 10 ⁻² Pa, and heating is performed. The heating temperature is kept at 500 ° C. for 30 minutes. Thereafter, cooling is performed, and after returning to atmospheric pressure with nitrogen gas, removal is performed.

Table 1 shows the presence or absence of the effect of reducing the discharge voltage when the reduced pressure heating step is provided and when the heating step is provided without reducing the pressure.

As shown in Table 1, the pressure in the reduced pressure heating step is effective even at a pressure of about 10 Pa, but it has been found that heating at atmospheric pressure has no effect. This is thought to be due to the influence of the vapor pressure of impure gas and the ease of re-adsorption. For this reason, it seems that an effect is reliably acquired, so that pressure is low.

As a result of further investigation, when the protective layer 9 is formed of a metal oxide selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide, the pressure in the reduced pressure heating process is optimally 1 × 10 ⁻² Pa to 50 Pa. It turned out to be. If it is lower than 1 × 10 ⁻² Pa, a change in the shape of the sealing layer appears, resulting in a problem with the airtightness of the PDP. When the pressure is higher than 50 Pa, there is a phenomenon that the discharge voltage of the PDP becomes abnormally high particularly in the protective layer containing calcium oxide. This is considered because the effect by a pressure reduction heating process is not acquired.

Also, the heating temperature is effective at 450 ° C. or higher. The upper limit temperature for heating was 600 ° C. because a glass substrate was used.

It is desirable to determine the start time of the reduced pressure heating process based on the composition of the sealing member. As the temperature rises in the sealing step, PDP sealing (sealing) by the sealing member starts, and is maintained at a certain temperature, and the sealing proceeds. In the present embodiment, pressure reduction is started during the temperature holding period. The temperature at that time is in the range of 450 ° C. to 600 ° C. Further, it is desirable that the temperature is 5 min to 10 min from the start of temperature holding to the start of pressure reduction. This is because the PDP sealing is insufficient when it is shorter than 5 minutes, and the decompression period is shortened when it is longer than 10 minutes.

As described above, in the present embodiment, the protective layer 9 is formed of a metal oxide selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide, and includes a reduced-pressure heating step before the sealing step. Therefore, it is possible to suppress discharge deterioration due to adsorption of impure gas and to suppress variation in discharge characteristics. Thereby, a low discharge voltage and a reduction in lighting failure can be realized at the same time.

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

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)
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 81 First dielectric layer 82 Second dielectric layer 91 Base film 92 Aggregated particles 92a Crystal particles

Claims

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 the display electrode of the first substrate and provided with a partition wall that partitions 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 metal oxide is formed of a metal oxide composed of at least two oxides selected from strontium and barium oxide, and the metal oxide has a specific orientation plane in the metal oxide. There is a peak between the minimum diffraction angle and the maximum diffraction angle generated from the simple substance of the oxide constituting the object, and the protective layer is subjected to a heating step in a reduced-pressure atmosphere before the sealing step. A method for manufacturing a plasma display panel.
The method for manufacturing a plasma display panel according to claim 1, wherein the pressure in the heating step in the reduced-pressure atmosphere is 10 Pa or less.
The method for manufacturing a plasma display panel according to claim 1, wherein a heating temperature in the heating step in the reduced-pressure atmosphere is 450 ° C. or more and 600 ° C. or less.