JP2003109511A - Plasma display panel - Google Patents

Abstract

(57) [Problem] To provide a plasma display panel used for an image display device or the like, which improves image display quality and stably maintains the image display quality for a long period of time. SOLUTION: A plasma display panel in which a first electrode and a second electrode constituting a main electrode pair are covered with an insulating layer with respect to a discharge gas, and a protective film covering the insulating layer is provided, wherein the plasma display panel is included in the protective film. The concentration of at least one of the four elements potassium, calcium, iron and chromium is adjusted to be 100 ppm or less for potassium and 100 ppm for calcium.
Hereinafter, the concentration ranges are as follows: iron: 10 ppm or less, chromium: 10 ppm or less.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventional plasma display panels are
The configuration shown in FIG. 4 is generally used.

This plasma display panel comprises a front panel 100 and a rear panel 200. The front panel 100 includes a scan electrode 102 on a front glass substrate 101.
a and sustain electrodes 102b are alternately formed in a stripe shape and further covered with a dielectric glass layer 103 and a protective film 104 made of magnesium oxide (MgO).

The rear panel 200 includes a rear glass substrate 20.
1, the address electrodes 202 are formed in a stripe shape, the electrode protection layer 203 is formed so as to cover the address electrodes 202, and the partition walls 204 are formed in a stripe shape on the electrode protection layer 203 so as to sandwich the address electrodes 202. Further partition wall 20
4 is provided with a phosphor layer 205 between them. Then, the front panel 100 and the rear panel 200 are attached to each other, and a discharge gas is enclosed in the space 210 partitioned by the partition wall 204 to form a discharge space. The phosphor layer is usually red for color display,
Phosphor layers of three colors of green and blue are sequentially arranged.

The discharge space 210 is filled with a discharge gas, for example, a mixture of neon and xenon, usually at a pressure of about 0.67 × 10 ⁵ Pa.

Next, a driving method of the plasma display panel will be described.

FIG. 5 is a block diagram showing a configuration of a driving circuit of the plasma display panel.

The drive circuit comprises an address electrode drive section 22.
0, the scan electrode driver 230, and the sustain electrode driver 240
It consists of and.

An address electrode driver 220 is connected to the address electrode 202 of the plasma display panel, a scan electrode driver 230 is connected to the scan electrode 102a, and a sustain electrode driver 240 is connected to the sustain electrode 102b.

Generally, in an AC type plasma display panel, one frame image is displayed in a plurality of subfields (S
A method of expressing gradation by dividing into F) is used. Then, in this method, 1SF is further divided into four periods in order to control the discharge of gas in the cell.
The four periods will be described with reference to FIG. Figure 6
Is a drive waveform in 1SF.

In FIG. 6, the setup period 25
At 0, wall charges are uniformly accumulated in all cells in the PDP in order to facilitate discharge. In the address period 260, the writing discharge of the cell to be turned on is performed. In the sustain period 270, the cell written in the address period 260 is lit and the lit state is maintained. Erase period 280
Then, the wall charge is erased to stop the lighting of the cell.

In the setup period 250, the scan electrode 1
A voltage higher than that of the address electrode 202 and the sustain electrode 102b is applied to 02a to discharge the gas in the cell. The charges generated thereby are accumulated on the wall surface of the cell so as to cancel the potential difference between the address electrode 202, the scan electrode 102a, and the sustain electrode 102b, and thus the scan electrode 102a.
Negative charges are accumulated as wall charges on the surface of the protective film in the vicinity, and positive charges are accumulated as wall charges on the surface of the phosphor layer near the address electrodes and the surface of the protective film near the sustain electrodes. Due to this wall charge, a wall potential having a predetermined value is generated between the scan electrode and the address electrode and between the scan electrode and the sustain electrode.

In the address period 260, when the cell is turned on, a voltage lower than that of the address electrode 202 and the sustain electrode 102b is applied to the scan electrode 102a, that is, the same as the wall potential between the scan electrode and the address electrode. A voltage is applied in the same direction and a voltage is applied between the scan electrode and the sustain electrode in the same direction as the wall potential, thereby causing write discharge. Thereby, the phosphor layer surface,
Negative charges are accumulated on the surface of the protective film, and positive charges are accumulated as wall charges on the surface of the protective film near the scanning side electrode. As a result, a wall potential having a predetermined value is generated between the sustain and scan electrodes.

In the sustain period 270, the scan electrodes 10 are
By applying a voltage higher than that of the sustain electrode 102b to 2a, that is, by applying a voltage between the sustain electrode and the scan electrode in the same direction as the wall potential, the sustain discharge is generated. As a result, cell lighting can be started.
Then, by applying a pulse so that the polarities of the sustain electrodes and the scan electrodes are alternately switched, it is possible to intermittently emit pulsed light.

In the erase period 280, by applying a narrow erase pulse to the sustain electrode 102b, incomplete discharge occurs and the wall charges disappear, so that erase is performed.

[0016]

By the way, when a television image is displayed because the number of scanning lines increases as the cell structure becomes finer, all sequences within one field = 1/60 [s]. Need to be finished. In order to respond to this, it is necessary to narrow the pulse width of the address pulse applied in the writing period to perform high-speed driving, but there is a "discharge delay" in which discharge is performed considerably delayed from the rising edge of the pulse. The probability of ending the discharge within the applied pulse width becomes low, and writing failure cannot occur in a cell that should be originally turned on without writing.

However, this "discharge delay" is reduced,
Whether or not the address discharge can be surely generated is largely related to the amount of electrons emitted from the protective film facing the discharge space.

Therefore, it is an object of the present invention to increase the electron emission amount by controlling the elemental composition of the protective film, reduce flicker in image display, and improve image display quality.

[0019]

In order to solve this problem, the present invention includes, as a protective film, four elements of potassium, calcium, iron and chromium, and at least one of the four elements is used. The concentration range is as follows.

[0020] Potassium: 100ppm or less Calcium: 100ppm or less Iron: 10ppm or less Chromium: 10ppm or less

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION First of all, it is considered that the main reason for the discharge delay is that the initial electrons, which act as a trigger when the discharge is started, are not easily released from the substrate surface into the discharge space.

Therefore, if it is possible to create a situation in which the initial electrons are likely to be emitted, it is considered that the discharge delay can be effectively prevented.

As a method for this, a method of increasing the drive pulse voltage at the time of addressing / sustaining the discharge or shortening the distance between the electrodes can be considered. However, since the increase in the pulse voltage has a relationship in which the breakdown voltage of the switching element of the drive circuit and the slew rate are contradictory to each other, the rise of the pulse becomes dull in the high breakdown voltage element, and there is a limit in suppressing the discharge delay time. Further, shortening the distance between the electrodes also lowers the height of the barrier ribs at the same time. However, if the height of the barrier ribs is lowered in this way, the discharge space itself is reduced, and the unit volume surrounding the plasma is reduced. Since the area of the wall that surrounds the discharge space increases, the efficiency decreases due to so-called wall loss, in which plasma disappears when it collides with the wall surface.

Therefore, the inventors of the present invention have a panel structure capable of preventing a discharge delay even if the conventional structure is followed without changing the structure of the drive circuit or the distance between the electrodes. As a result of searching, they came to the present invention.

That is, according to the present invention, the first and second electrodes constituting the main electrode pair are covered with an insulating layer against discharge gas, and a plasma display panel is provided with a protective film covering the insulating layer. , The protective film is potassium [K],
Calcium [Ca], iron [Fe] and chromium [Cr]
Of the four elements, and at least one of the four elements is in the following concentration range.

Potassium: 100 ppm or less Calcium: 100 ppm or less Iron: 10 ppm or less Chromium: 10 ppm or less In the present invention, the protective film contains silicon [Si] in a concentration range of 500 to 15000 ppm.

Further, in the present invention, as a magnesium oxide raw material for producing a protective film of a plasma display panel, four kinds of elements of potassium, calcium, iron and chromium are contained, and at least one of the four kinds of elements is included. The species used are those having the following concentration ranges.

Potassium: 100 ppm or less Calcium: 100 ppm or less Iron: 10 ppm or less Chromium: 10 ppm or less Further, as the magnesium oxide raw material, silicon is 500
What is contained in the concentration range of -15000 ppm is used.

As a result, in the surface layer of the dielectric layer,
Impurity elements that inhibit electron emission will be reduced, and as a result, trigger electrons for address discharge and sustain discharge will be easily emitted, so that the discharge delay at the time of address discharge and sustain discharge can be suppressed, It is possible to improve the responsiveness of discharge generation to voltage application and display a good image.

Further, in the present invention, K, Ca, F
Since the electron emission amount is improved by defining the concentration ranges of e and Cr, it is possible to suppress the “discharge delay” while maintaining the effect of adding Si. Furthermore, K, C
From the result that the electron emission ability is improved as compared with the MgO film which only defines the concentration ranges of a, Fe and Cr, it is considered that there is a synergistic effect with the addition of Si.

A plasma display panel according to an embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 1 shows an AC surface discharge type plasma display panel 1 (hereinafter simply referred to as a PD according to an embodiment of the present invention.
It is a perspective view showing (P1).

In this PDP 1, discharge is generated in the discharge space 30 by applying a pulsed voltage to each electrode, and visible light of each color generated on the rear panel PA2 side due to the discharge is emitted to the main panel of the front panel PA1. It is an AC surface discharge type PDP that transmits from the surface.

In the front panel PA1, a plurality of pairs of scan electrodes 12a and sustain electrodes 12b are arranged in a stripe shape with a discharge gap 12C (for convenience, one pair is shown).
A dielectric glass layer 13 is formed on the formed front glass substrate 11 so as to cover the surface 11a, and a protective film 1 made of MgO so as to cover the dielectric glass layer 13.
4 is formed.

The protective film 14 is formed by a manufacturing method that prevents the reduction of adsorbed gas and the formation of an altered layer as shown in the present invention.

The rear panel PA2 protects the address electrodes on the rear glass substrate 16 in which the address electrodes 17 are arranged in stripes so as to be orthogonal to the scan electrodes 12a and the sustain electrodes 12b, and at the same time, the visible light front panel. The electrode protection layer 18 having a function of reflecting to the side is the address electrode 17
Is formed so as to cover the address protection layer 18 and extends in the same direction as the address electrodes 17 and partition walls 19 are erected so as to sandwich the address electrodes 17, and a phosphor layer is provided between the partition walls 19. 20 is provided.

The PDP having the above configuration is driven by using the drive circuit shown in FIG. 5 based on the drive waveform shown in FIG. Address electrode 17 is connected to address driver 220, scan electrode 12a is connected to scan electrode driver 230, and sustain electrode 12b is connected to sustain electrode driver 240.

As described above, MgO is mainly used for the PDP protective film at present, and the vapor deposition method or the sputtering method is generally used for the production of this protective film.

By the way, in the method for producing the raw material for forming the MgO film, the low-purity MgO purified from seawater is electromelted and slowly cooled to grow a single crystal.
A general method is to obtain high-purity MgO, and this high-purity MgO is crushed, crushed, and sorted to be used as a raw material. The shape of the raw material varies, and the powder-shaped material may be used as it is, or the powder-shaped material may be used as a sintered body by pressurizing and heating and compressing it, or at the stage of pulverizing, it may be about several mm. It can be used as it is as a single crystal.

In the present invention, K, Ca, Fe and Cr, which are elements for controlling the concentration, are contained in the low-purity MgO stage obtained from seawater in the above process, but the plasma of the present invention is used. As a raw material used for a display panel, a highly pure single crystal part is desirable. Further, since Fe and Cr may be mixed during crushing, it is effective to use a non-metal material for the crushing tool.

On the other hand, regarding Si, this is also K, Ca, F
Similarly to e and Cr, it is contained at the stage of low-purity MgO obtained from seawater, but is 500 in the present invention.
A concentration of ~ 15000 ppm is required. Therefore, once the high-purity MgO raw material is obtained by the above method,
A method of adding Si to it is desirable. For example, when powdered high-purity MgO is used, there is a method in which a powdered Si compound is mixed and used, or the mixture is used as a sintered body. When using a single crystal,
A method of using a Si compound and mixing them as a vapor deposition source, or a binary vapor deposition method of MgO and Si compounds,
A sputtering method or the like is possible.

In the above description, only the method of refining from seawater as the MgO raw material was described.
There is also a method of obtaining a gO raw material, and in this case as well, the present invention can be applied by increasing the component purity.

Next, the method for producing the protective film of the present invention will be described.

In the present invention, a vapor deposition method was used. Using the MgO vapor deposition source whose components were controlled as described above, a pierce-type electron beam gun was used as a heating source in an oxygen atmosphere to simultaneously heat to form a desired film.

Here, the amount of electron beam current, the amount of oxygen partial pressure, the substrate temperature, etc. during film formation do not have a great influence on the composition of the protective layer after film formation, and may be set arbitrarily.

The film forming method is not limited to the vapor deposition method, and a sputtering method, an ion plating method, or the like can be considered. In this case as well, the components of the target material and the raw materials are controlled, and the film is formed by the material. Similar effects can be obtained.

Further, regarding Si, as described above,
A method of mixing with the obtained high-purity MgO and using it, or a method of using it as a vapor deposition source in a binary system of MgO and Si compounds, a sputtering target, etc. is effective.

The results of component analysis of the protective film obtained by the present invention are shown in FIG. The analysis method of FIG. 2 is TOF-SIM.
Although S is used, almost the same result is obtained from the MgO film of the present invention formed on a sapphire substrate.

FIG. 3 shows the measurement results of the electron emission characteristics from the protective film obtained by the present invention. Figure 3
In the measurement method (1), a sample in which each MgO film is arranged on the discharge surface is subjected to in-plane discharge, and the amount of electric charge flowing through the electrodes arranged opposite to each other is measured. From these results, compared to the conventional technology, Si
The electron emission amount is greatly reduced in the case of adding only Si.
It can be confirmed that the electron emission amount in the case where the concentration ranges of e and Cr are defined is larger than that in the conventional technique.

This is considered to be due to the fact that the impurity element, which hindered the electron emission ability, reduced the concentrations of K, Ca, Fe, and Cr, and thereby brought out the electron emission characteristic originally possessed by MgO.

Next, a method of manufacturing the PDP will be described.

First, a method of manufacturing the front panel PA1 will be described. The scanning electrode 12 is formed on the front glass substrate 11.
a and sustain electrodes 12b are formed so as to be arranged alternately.

The scan electrodes 12a and the sustain electrodes 12b are metal electrodes and are formed by depositing platinum by an electron beam evaporation method and then patterning by a lift-off method. Each scan electrode 12a and sustain electrode 12b may be formed by a pair of a transparent electrode such as ITO and a metal electrode.

Next, a dielectric glass layer is formed so as to cover the scan electrodes 12a and the sustain electrodes 12b by printing by a known printing method such as a screen printing method and then firing.

Next, MgO is formed on the surface of the dielectric glass layer 13.
To form the protective film 14. Specifically, it is formed by depositing a MgO thin film on the surface of the dielectric glass layer 13 by an electron beam evaporation method.

Next, a method of manufacturing the back panel PA2 will be described. The back panel PA2 is the back glass substrate 1
6 is formed by forming an address electrode 17 on 6 and covering it with an electrode protection layer 18, forming partition walls 19 on the surface of this electrode protection layer 18, and then forming a phosphor layer 20. The address electrodes 17 are formed on the rear glass substrate 16 in the same manner as the scan electrodes 12a and the sustain electrodes 12b.

The electrode protection layer 18 is printed on the address electrodes 17 by a printing method such as a screen printing method,
It is a thin film formed by firing and containing titanium oxide (TiO ₂ ) particles in a glass composition similar to that of the dielectric glass layer 13.

The partition wall 19 is formed by applying a partition wall forming raw material by a method such as a screen printing method, a lift-off method, or a sandblasting method, firing this, and then subjecting the top surface of the partition wall to a processing treatment. .

The phosphor layer 20 is formed by a method such as a screen printing method or a nozzle spraying method. In addition, three colors of red, green, and blue are used for the phosphor. Then, for example, the following can be used.

Red phosphor: Y ₂ O ₃ : Eu ³⁺ Green phosphor: Zn ₂ SiO ₄ : Mn ²⁺ Blue phosphor: BaMgAl ₁₀ O ₁₇ : Eu ²⁺ Next, front panel PA1 and back panel PA2 Are aligned and bonded so that the scan electrodes 12a, the sustain electrodes 12b and the address electrodes 17 are orthogonal to each other, and then the partition 19
A discharge gas such as He
The PDP 1 is obtained by filling a -Xe-based or Ne-Xe-based inert gas at a predetermined pressure.

[0061]

As described above, according to the present invention, in the plasma display panel, potassium: 100 pp for at least one element selected from the four elements of potassium, calcium, iron and chromium contained in the protective film.
m or less, calcium: 100 pm or less, iron: 10 ppm
Below, by setting the concentration range of chromium to 10 ppm or less, the concentration of the impurity element that hinders the electron emission characteristics of the protective film can be reduced and the electron emission capability can be improved. As a result, the address discharge and sustain discharge Therefore, the trigger electrons are easily emitted, so that the discharge delay at the time of the address discharge or the sustain discharge can be suppressed, the responsiveness of the discharge occurrence to the voltage application can be improved, and a good image can be displayed. .

[Brief description of drawings]

FIG. 1 is a perspective view showing a plasma display panel according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an impurity analysis result of the MgO film of the panel.

FIG. 3 is a characteristic diagram showing a comparison of electron emission amounts from MgO films.

FIG. 4 is a perspective view showing a conventional plasma display panel.

FIG. 5 is a block diagram showing an image display device in which a driving sea line is connected to a plasma display panel.

FIG. 6 is a time chart showing driving waveforms of the plasma display panel.

[Explanation of symbols]

PA1 front panel PA2 rear panel 1 Plasma display panel (PDP) 11 Front glass substrate 12a scanning electrode 12b Sustain electrode 12c discharge gap 13 Dielectric glass layer 14 Protective film 16 Rear glass substrate 17 address electrodes 18 Electrode protection layer 19 partitions 20 Phosphor layer 30 discharge space

Claims (5)

[Claims] 1. A plasma display panel in which first and second electrodes forming a main electrode pair are covered with an insulating layer against discharge gas, and a protective film covering the insulating layer is arranged. Is a potassium, calcium, iron and chromium element, and at least one of the four elements is in the following concentration range. Potassium: 100 ppm or less Calcium: 100 ppm or less Iron: 10 ppm or less Chromium: 10 ppm or less 2. The plasma display panel according to claim 1, wherein the protective film contains silicon in the following concentration range. Silicon: 500-15000ppm 3. The plasma display panel according to claim 1, wherein the main material of the protective film is magnesium oxide. 4. A magnesium oxide raw material for a protective film of a plasma display panel, wherein the raw material contains four elements of potassium, calcium, iron and chromium.
A magnesium oxide raw material for a protective film of a plasma display panel, characterized in that at least one of the four elements is in the following concentration range. Potassium: 100 ppm or less Calcium: 100 ppm or less Iron: 10 ppm or less Chromium: 10 ppm or less 5. The magnesium oxide raw material for a protective film of a plasma display panel according to claim 4, wherein silicon is contained in the raw material in the following concentration range. Silicon: 500-15000ppm