JP2010135197A - Plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a protective layer with high electron emission characteristics and high charge retention characteristics, and thereby, to obtain a PDP endowed with high-definition and high-luminance display performance and capable of being driven at a low voltage. <P>SOLUTION: The plasma display panel is provided with a front plate with a dielectric layer 8 formed so as to cover a display electrode 6 formed on a substrate 3, and furthermore, with a protective layer 9 formed on the dielectric layer 8. The protective layer 9 has a base layer 91 formed of MgO, a layer 91a covering the base layer 91 and with a γ factor smaller than that of MgO, and agglomerated particles 92 of MgO crystal particles 92a adhered on the layer 91a with the smaller γ factor than the MgO. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  Since a plasma display panel (hereinafter referred to as PDP) can achieve high definition and high screen, 65-inch class televisions and the like have been developed. In recent years, PDP has been applied to high-definition televisions having more than twice the number of scanning lines as compared with the conventional NTSC system, and a PDP containing no lead component is required in consideration of environmental problems.

  A PDP basically includes a front plate and a back plate. The front plate is a glass substrate made of sodium borosilicate glass by a float method, a display electrode composed of a striped transparent electrode and a bus electrode formed on one main surface of the glass substrate, and a display electrode It comprises a dielectric layer that covers and acts 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 composed of a base dielectric layer that covers the address electrodes, a partition formed on the base dielectric layer, and a phosphor layer that emits red, green, and blue light formed between the partitions. ing.

  The front plate and the back plate are hermetically sealed with their electrode forming surfaces facing each other, and Ne and Xe discharge gases are sealed at a pressure of 400 Torr to 600 Torr in a discharge space partitioned by a partition wall. 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 such a PDP, the protective layer formed on the dielectric layer of the front plate can protect the dielectric layer from ion bombardment due to discharge, emit initial electrons for generating address discharge, and the like. . Protecting the dielectric layer from ion bombardment is an important role to prevent discharge voltage rise, and emitting initial electrons to generate address discharge can prevent address discharge mistakes that cause image flicker. 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, an example of adding impurities to MgO or an example of forming MgO particles on the MgO protective layer is disclosed (for example, , See Patent Documents 1, 2, and 3).
JP 2002-260535 A JP 11-339665 A JP 2006-59779 A

  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 characteristic from the protective layer determines the pixel of the PDP, it is very important to control the electron emission characteristic.

  Therefore, attempts have been made to improve the electron emission characteristics by mixing impurities in the protective layer. However, when the electron emission characteristics are improved by mixing impurities in the protective layer, the charge is accumulated in the protective layer, and the attenuation rate at which the electric charge decreases as time goes on increases. Therefore, it is necessary to take measures such as increasing the applied voltage to suppress this.

  As described above, the protective layer has a high electron emission characteristic and also has two contradictory characteristics such as a low charge decay rate as a memory function, that is, a high charge retention characteristic. There was a problem of not becoming.

  In order to satisfy these characteristics, there is an example in which MgO particles are formed on the MgO protective layer. However, in such a configuration, the MgO particles can have high electron emission characteristics, but the charge as a memory function. As for the charge retention characteristic, the voltage applied to the scan electrode (hereinafter referred to as the Vscn lighting voltage. The charge retention characteristic is lower when the Vscn lighting voltage is lower. There is a problem that a higher voltage than before has to be applied.

  The present invention has been made in view of such a problem, and realizes a protective layer having high electron emission characteristics and high charge retention characteristics, and thus has high-definition and high-luminance display performance and is driven at a low voltage. An object is to realize a PDP capable of performing the above.

  In order to achieve the above object, the PDP of the present invention includes a front plate in which a dielectric layer is formed so as to cover a display electrode formed on a substrate and a protective layer is formed on the dielectric layer. Comprises a MgO underlayer, a layer with a γ coefficient smaller than MgO covering the underlayer, and agglomerated particles of MgO crystal particles adhering onto the layer with a γ coefficient smaller than MgO. To do.

  According to the present invention, since a protective layer having high electron emission characteristics and high charge retention characteristics can be realized, a high-definition, high-brightness display performance and low-voltage drive PDP can be realized. It becomes possible to do.

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

  FIG. 1 is a cross-sectional perspective view showing a schematic structure of a PDP according to an embodiment of the present invention. In the PDP 1, a front plate 2 made of a front glass substrate 3 and the like and a back plate 10 made of a back glass substrate 11 and the like are arranged to face each other, and an outer periphery thereof is sealed by a sealing material (not shown) made of glass frit or the like. It is hermetically sealed (sealed). The discharge space 16 inside the sealed PDP 1 is filled with a discharge gas such as Ne or Xe at a pressure of 400 Torr to 600 Torr.

  On the front glass substrate 3 of the front plate 2, a pair of strip-like display electrodes 6 made up of scanning electrodes 4 and sustain electrodes 5 and black stripes (light-shielding layers) 7 are arranged in a plurality of rows in parallel with each other. A dielectric layer 8 serving as a capacitor is formed on the front glass substrate 3 so as to cover the display electrode 6 and the light shielding layer 7, and a protective layer 9 made of magnesium oxide (MgO) is formed on the surface. Has been.

  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. For each address electrode 12, a phosphor layer 15 that emits red, green, and blue light by ultraviolet rays is sequentially applied to the grooves between the barrier ribs 14 and formed.

  A discharge cell is formed at a position where the display electrode 6 (scanning electrode 4 and sustaining electrode 5) and the address electrode 12 intersect, and the red, green, and blue phosphor layers 15 arranged in the longitudinal direction of the display electrode 6. A discharge cell having a pixel becomes a pixel for color display.

FIG. 2 is a cross-sectional view showing a schematic structure of the front plate 2 in the PDP 1 according to the embodiment of the present invention, and FIG. As shown in FIG. 2, a display electrode 6 including a scanning electrode 4 and a sustain electrode 5 and a black stripe (light shielding layer) 7 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 ), 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.

  Next, the configuration of the protective layer 9 in the PDP according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view showing a schematic structure of the protective layer 9. The protective layer 9 includes a base layer 91 made of MgO containing Al as an impurity on the dielectric layer 8, and the base layer. A layer 91a (hereinafter referred to as a low γ layer 91a) having a smaller γ coefficient (secondary electron emission coefficient) than MgO is formed on the surface layer 91, and MgO, which is a metal oxide, is formed on the low γ layer 91a. A plurality of agglomerated particles 92 in which several crystal particles 92 a are agglomerated are discretely distributed almost uniformly over the entire surface.

  Here, the low γ layer 91a is preferably formed of magnesium carbonate in consideration of consistency with the base layer 91, light transmittance, and productivity.

  In addition, the aggregated particles 92 are those in which crystal particles 92a having a predetermined primary particle size are aggregated or necked as shown in FIG. 3, and are not bonded with a large binding force as a solid, Multiple primary particles form an aggregated body due to static electricity, van der Waals force, etc., and they are combined with such a force that some or all of them become primary particles by an external stimulus such as ultrasound. It is what you are doing. 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.

  Next, the manufacturing process of the protective layer 9 in the PDP according to the embodiment of the present invention will be described with reference to FIG. First, a base layer deposition step (A1) of forming a base layer 91 made of MgO containing Al as an impurity by vapor deposition on the front plate formed up to the dielectric layer, and then on the base layer 91, A step (A2) of forming a paste film containing aggregated particles 92 in which several MgO crystal particles 92a that are metal oxides are aggregated, a step (A3) of drying the paste film, and then firing. The protective layer 9 is formed by the step (A4) and the step (A5) of forming the low γ layer 91a of magnesium carbonate on the base layer 91 by exposure in a carbon dioxide atmosphere.

  Next, a description will be given of the results of an experiment conducted for confirming the performance of the PDP according to an embodiment of the present invention that includes the protective layer 9 described above.

  First, a PDP having a protective layer having a different configuration was made as a prototype. Prototype 1 is a PDP in which aggregated particles obtained by aggregating crystal particles made of metal oxide on a protective layer made of MgO doped with impurities such as Al and Si are attached so as to be distributed almost uniformly over the entire surface. Prototype 2 is a PDP according to an embodiment of the present invention. As described above, low γ layer 91a is formed on base layer 91 made of MgO, and crystal particles 92a made of metal oxide are further aggregated thereon. The agglomerated particles 92 are adhered so as to be distributed almost uniformly over the entire surface.

  In the prototype 1, MgO single crystal particles are used as the metal oxide, and in the prototype 2, the low γ layer 91a is formed of magnesium carbonate. Here, as described above, the low γ layer 91a formed of magnesium carbonate is formed by adhering the aggregated particles 92 on the MgO underlayer 91 and then exposing to the carbon dioxide atmosphere. It is.

  The electron emission performance and charge retention performance of the PDP having these two types of protective layer configurations were examined. The electron emission performance is a numerical value indicating that the larger the electron emission amount, the greater the amount of electron emission. The initial electron emission amount can be measured by irradiating the surface with ions or an electron beam and measuring the amount of electron current emitted from the surface, but it is difficult to evaluate the surface of the front plate in a nondestructive manner. Accompanied by. Therefore, as described in Japanese Patent Application Laid-Open No. 2007-48733, among the delay times at the time of discharge, a numerical value called a statistical delay time, which is a measure of the ease of occurrence of discharge, is measured, and the reciprocal thereof is integrated. Thus, it is known that the numerical value corresponds linearly to the amount of initial electron emission, and here, this numerical value is used for evaluation. This delay time at the time of discharge means the time of discharge delay that is delayed from the rise 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 to the discharge space. It is considered as a main factor that it is difficult to be released into the inside.

  In addition, as an indicator of the charge retention performance, a voltage value of a voltage applied to the scan electrode (hereinafter referred to as a Vscn lighting voltage) necessary for suppressing the charge emission phenomenon when manufactured as a PDP was used. That is, the lower the Vscn lighting voltage, the higher the charge retention capability. Since this can be driven at a low voltage even in the panel design of the PDP, it is possible to use components having a small withstand voltage and capacity as the power source and each electrical component. In the current product, a semiconductor switching element such as a MOSFET for sequentially applying the scanning voltage to the panel uses an element having a withstand voltage of about 150 V, and the Vscn lighting voltage is 120 V in consideration of variation due to temperature. It is desirable to keep it below.

  The results of examining these electron emission performance and charge retention performance are shown in FIG. As is apparent from FIG. 5, the prototype 2 can reduce the Vscn lighting voltage to 120 V or less in the evaluation of the charge retention performance, and is superior to the prototype 1 in the relative comparison with the prototype 1. In addition, in terms of electron emission performance, the prototype 2 is better than the prototype 1, and thus the prototype 2 which is a PDP according to an embodiment of the present invention has an electron emission characteristic, It can be seen that good charge retention characteristics are obtained.

  That is, as a result of studying the PDP according to an embodiment of the present invention, it is possible to obtain a protective layer having an electron emission capability of characteristics higher than that of the prototype 1 and a charge retention capability of Vscn lighting voltage of 120 V or less. Therefore, it is possible to satisfy both the electron emission capability and the charge retention capability required for the protective layer in the PDP, in which the number of scanning lines increases and the cell size tends to decrease due to high definition. . As a result, a high-definition, high-luminance display performance and low power consumption PDP can be realized.

  In addition, by using a magnesium carbonate layer as the low γ layer, it has high-definition and high-luminance display performance and has low power consumption without adversely affecting light transmission, sputtering resistance, and voltage characteristics during life operation. This is preferable because the PDP can be realized.

  As described above, the present invention is useful for providing a large-screen, high-definition plasma display device.

1 is a cross-sectional perspective view showing a schematic structure of a PDP according to an embodiment of the present invention. Sectional drawing which shows schematic structure of the front plate in PDP by one embodiment of this invention Sectional drawing which shows schematic structure of the protective layer in PDP by one embodiment of this invention The figure which shows the flow of the manufacturing process of the protective layer in PDP by one embodiment of this invention Figure showing the results of electron emission performance and charge retention performance of the protective layer

Explanation of symbols

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 81 First dielectric layer 82 Second dielectric layer 91 Base layer 91a Low γ layer (Layer with smaller γ coefficient (secondary electron emission coefficient) than MgO)
92 Aggregated particles 92a Crystal particles

Claims (2)

A dielectric layer is formed so as to cover the display electrode formed on the substrate, and a front plate having a protective layer formed on the dielectric layer is provided, and the protective layer covers the base layer made of MgO and the base layer A plasma display panel comprising: a layer having a γ coefficient smaller than MgO; and agglomerated particles of MgO crystal particles attached on the layer having a γ coefficient smaller than MgO. The plasma display panel according to claim 1, wherein the layer having a γ coefficient smaller than MgO is a layer of magnesium carbonate.

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