JP4110857B2 - Method for manufacturing plasma display panel and raw material for producing protective layer thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma display panel (hereinafter referred to as PDP) used for an image display device and the like, and more particularly to a material for forming a protective layer of the PDP.
[0002]
[Prior art]
In an AC surface discharge type PDP having a protective layer, a driving voltage is lowered by covering an electrode for main discharge with a dielectric layer and performing memory driving. However, the dielectric layer is altered by ion bombardment caused by discharge, and the drive voltage rises. Therefore, it is necessary to form a protective layer that protects the dielectric layer. In general, a material having high sputtering resistance such as magnesium oxide (hereinafter referred to as MgO) is used for the protective layer.
[0003]
Incidentally, since the number of scanning lines increases as the cell structure becomes higher in definition, it is necessary to end all sequences within 1 field = 1/60 [s] when displaying a television image. In order to respond to this, it is necessary to perform high-speed driving by narrowing the pulse width of the address pulse applied during the writing period. However, since there is a “discharge delay” in which the discharge is performed with a considerable delay from the rise of the pulse, the probability that the discharge ends within the applied pulse width is low, and writing or the like can be performed on the cell that should originally be lit. In some cases, lighting failure occurred.
[0004]
The main reason for the discharge delay is that the initial electrons that are triggered when the discharge is started are not easily released from the protective layer into the discharge space. Thus, since the protective layer faces the discharge space, the drive voltage changes depending on the physical properties of the protective layer, and is related to the discharge delay. As measures against discharge delay other than the physical properties of the protective layer, there are methods of increasing the drive pulse voltage at the time of addressing and maintaining the discharge, or shortening the distance between the electrodes.
[0005]
[Problems to be solved by the invention]
However, the increase in the drive 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. Therefore, in the high breakdown voltage element, the rise of the pulse is dull and there is a limit to the suppression of the discharge delay time. Further, shortening the distance between the electrodes simultaneously reduces the height of the barrier ribs. However, if the height of the barrier ribs is reduced in this way, the discharge space itself is reduced. As a result, since the area of the wall surrounding the discharge space per unit volume surrounding the plasma increases, there is a problem that the light emission efficiency decreases due to so-called wall loss that the plasma disappears when it collides with the wall surface. .
[0006]
The present invention has been made in view of such a problem, and an object of the present invention is to suppress discharge delay, improve the responsiveness of occurrence of discharge to voltage application, and display a good image.
[0007]
[Means for Solving the Problems]
In the method for manufacturing a PDP of the present invention, the electrodes constituting the main electrode pair are covered with a discharge gas by an insulating layer, a protective layer made of an alkaline earth metal oxide covering the insulating layer is disposed, and the protective layer is deposited. The germanium (hereinafter referred to as Ge) contained in the raw material for producing the protective layer produced by the method is in a concentration range of 300 to 8000 ppm by weight. The protective layer having this Ge concentration range forms an impurity level between the valence band and the conduction band, and the electron emission capability is improved. By setting the Ge concentration range to 300 to 8000 ppm by weight, the discharge delay time is reduced, flicker is not visually recognized, and a good image is obtained.
[0008]
The method for producing a PDP of the present invention is characterized in that the protective layer is MgO. By making the protective layer MgO, the electron emission capability is further improved.
[0009]
In the method for producing the PDP of the present invention, the raw material for producing the protective layer contains Ge in an amount of 300 to 8000 ppm by weight , and silicon (hereinafter referred to as Si) in a concentration range of 500 to 15,000 ppm by weight. Features. If the concentration range of Ge and Si is the above range, Ge improves the electron emission capability, and Si forms a film such as Mg ₂ SiO ₄ and MgSiO _{3 on the} surface of MgO to prevent adsorption of CO ₂ and H ₂ O. Impurity gas generation from the protective layer to the discharge space is prevented. As a result, an image with a small discharge delay and no flicker is generated, and no impurity gas is generated, so that the PDP is prevented from being deteriorated and the life of the PDP is extended.
[0011]
Moreover, the material for the protective layer of the PDP according to the present invention is such that the electrode constituting the main electrode pair is covered with a discharge gas by an insulating layer, and the protective layer of the PDP formed by arranging the protective layer covering the insulating layer is formed by vapor deposition. A raw material to be produced, wherein Ge is MgO contained in a concentration range of 300 to 8000 ppm by weight.
[0012]
The raw material for producing the protective layer of the PDP of the present invention is characterized in that Si is further contained in the above MgO in a concentration range of 500 to 15000 ppm by weight. In this way, by using a material in which the concentration range of Ge and further Si is defined as a raw material for producing the protective layer , a protective layer in which the concentration of the above-mentioned element is regulated can be easily and reliably produced. .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 is a partial perspective view of an AC surface discharge type PDP. This AC surface discharge type PDP generates a discharge in the discharge space 30 by applying a pulsed voltage to each electrode, and the visible light of each color generated on the back panel PA2 side with the discharge is converted into the front panel PA1. This is an AC surface discharge type PDP that is transmitted from the main surface.
[0015]
The front panel PA1 has a dielectric so as to cover the surface 11a on a front glass substrate 11 in which a plurality of pairs of scan electrodes 12a and sustain electrodes 12b are arranged in a stripe pattern (for convenience, one pair is shown in the figure). A glass layer 13 is formed. Further, a protective layer 14 is formed so as to cover the dielectric glass layer 13.
[0016]
The structure of the back panel PA2 is as follows. The address electrodes 17 are on the rear glass substrate 16 and are arranged in stripes so as to be orthogonal to the scan electrodes 12a and the sustain electrodes 12b. The electrode protection layer 18 is formed so as to cover the address electrodes 17 and protects the address electrodes 17 and has a function of reflecting visible light to the front panel side PA1. A partition wall 19 is erected on the electrode protection layer 18 in the same direction as the address electrode 17 so as to sandwich the address electrode 17, and a phosphor layer 20 is disposed between the partition walls 19.
[0017]
FIG. 2 is a block diagram showing an image display apparatus configured by connecting a drive circuit to the PDP of the present invention. The PDP is connected to the address electrode driver 220 via the address electrode 17, the scan electrode driver 230 via the scan electrode 12a, and the sustain electrode driver 240 via the sustain electrode 12b.
[0018]
FIG. 3 is a diagram for explaining a driving method of an image display apparatus configured by connecting a driving circuit to the PDP. In general, in the AC surface discharge type PDP, a method of expressing gradation by dividing one frame of video into a plurality of subfields (hereinafter referred to as SF) is used. In this method, in order to control the discharge of gas in the cell, 1S. F. Is further divided into four periods. FIG. F. It is a time chart which shows the inside drive waveform.
[0019]
In FIG. 3, wall charges are uniformly accumulated in all cells in the PDP in order to facilitate discharge in the setup period 25. In the address period 26, the write discharge of the cells to be lit is performed. In the sustain period 27, the cells written in the address period 26 are turned on and kept on. In the erase period 28, lighting of the cell is stopped by erasing the wall charges.
[0020]
In the setup period 25, a voltage higher than that of the address electrode 17 and the sustain electrode 12b is applied to the scan electrode 12a to discharge the gas in the cell. The charges generated thereby are accumulated on the cell wall so as to cancel the potential difference among the address electrodes 17, the scan electrodes 12a and the sustain electrodes 12b. As a result, negative charges are accumulated as wall charges on the surface of the protective layer near the scan electrode 12a, and positive charges are accumulated on the surface of the phosphor layer near the address electrode 17 and the surface of the protective layer near the sustain electrode 12b. Accumulated as wall charges. Due to this wall charge, a wall potential having a predetermined value is generated between scan electrode 12a and address electrode 17, and between scan electrode 12a and sustain electrode 12b.
[0021]
In the address period 26, when the cell is turned on, a voltage lower than that of the address electrode 17 and the sustain electrode 12b is applied to the scan electrode 12a. That is, a voltage is applied between the scan electrode 12a and the address electrode 17 in the same direction as the wall potential, and a voltage is also applied between the scan electrode 12a and the sustain electrode 12b in the same direction as the wall potential, thereby causing a write discharge. Cause it to occur. As a result, negative charges are accumulated on the phosphor layer surface and the protective layer surface, and positive charges are accumulated as wall charges on the protective layer surface near the scanning electrode 12a. As a result, a predetermined wall potential is generated between sustain electrode 12b and scan electrode 12a. At this time, there is a discharge delay from the time when a voltage is applied between the scan electrode 12a and the address electrode 17 until the write discharge is generated. Further, if the address discharge does not occur within the address time of each scan electrode, an address error occurs, no sustain discharge occurs, and the image flickers and appears in the image. In addition, when the resolution is further increased, the address time assigned to each scan electrode is shortened, and the probability of writing errors is increased.
[0022]
In the sustain period 27, a higher voltage is applied to the scan electrode 12a than the sustain electrode 12b. That is, a sustain discharge is generated by applying a voltage in the same direction as the wall potential between the sustain electrode 12b and the scan electrode 12a. As a result, cell lighting can be started. Then, by applying a pulse so that the polarity is alternately switched between the sustain electrode 12b and the scan electrode 12a, pulse light emission can be intermittently performed.
[0023]
In the erase period 28, an incomplete discharge is generated by applying a narrow erase pulse to the sustain electrode 12b, and the wall charges disappear, so that erase is performed.
[0024]
Next, the protective layer in the structure of the above PDP is the point of the present invention, and its manufacturing method and operational effects will be described.
[0025]
First, a method for manufacturing a protective layer in which only Ge is controlled in MgO will be described. Using a GeO-controlled MgO vapor deposition source, a piercing electron beam gun is heated as a heating source in an oxygen atmosphere to form a desired film. Here, the amount of electron beam current, the amount of oxygen partial pressure, the substrate temperature, etc. at the time of film formation do not have a great influence on the composition of the protective layer after film formation, and may be arbitrarily set. An example of the setting is shown below. .
[0026]
Ultimate vacuum: 5.0 × 10 ⁻⁴ Pa or less Deposition substrate temperature: 200 ° C. or more Deposition pressure: 3.0 to 8.0 × 10 ⁻² Pa
In addition, although only the vapor deposition method was described in the manufacturing method of the above protective layer, not limited to this method, a sputtering method, an ion plating method, and the like are also conceivable. In this case also, the target material and the raw material components are controlled, The same effect can be obtained by depositing the material.
[0027]
Further, a method of using Ge mixed with high-purity MgO or a method of using it as a vapor deposition source, a sputtering target, etc. in a binary system of MgO and Ge compounds is effective.
[0028]
Here, as a raw material of the protective layer, a MgO vapor deposition source in which a Ge concentration range of 40 to 21,000 ppm by weight was controlled was prepared. And the discharge delay time of the panel with respect to the protective layer of each Ge density | concentration was measured. The result is shown in FIG. The discharge delay time indicates the time from when a voltage is applied between the scan electrode to the address electrode in the address period until the discharge occurs. In the panel using the protective layers having the respective Ge concentrations, the write discharge was observed, the write discharge luminescence was averaged 100 times, and the time when the write discharge luminescence peaked was defined as the time when the discharge occurred. Further, when actually confirmed by video display, flicker was not visually recognized when the discharge delay time was 2700 ns or less, and it was determined that the display quality was good.
[0029]
As a result, the image display quality is good, that is, the discharge delay time is 2700 ns or less when the concentration of Ge contained in MgO is in the range of 300 to 8000 ppm by weight. That is, as the protective layer material, MgO containing Ge in a concentration range of 300 to 8000 ppm by weight is effective in reducing the discharge delay.
[0030]
Further, when the protective layer made of MgO adsorbs H ₂ O and CO ₂ , the surface thereof is transformed into Mg (OH) ₂ , MgCO _{3 and the} like. Thereafter, a panel is formed by the front panel and the back panel having a protective layer. When the panel is turned on in this state, it is dissociated by energy such as ion bombardment caused by discharge, and H ₂ O, CO ₂ , or ions thereof are released into the panel as an impurity gas. These impurity gases promote deterioration of the phosphor and a decrease in wear resistance due to discharge of the protective layer, and the panel has a short lifetime. Therefore, in order to prevent the MgO surface from being altered, Si was further added to the MgO added with Ge. The purpose of this is to form a Si oxide film on the surface of the protective layer and prevent the surface of the protective layer from being transformed into Mg (OH) ₂ , MgCO ₃ or the like. Based on these facts, a method for manufacturing a protective layer in which Mg and Ge components are controlled will now be described. A protective layer is formed under the same deposition conditions as described above using an MgO deposition source in which Ge is 300 ppm by weight in MgO and Si is controlled in various weight concentrations. In addition, a protective layer is similarly formed using a MgO vapor deposition source in which only the Ge concentration is changed from 300 ppm by weight to 1000, 5000, and 8000 ppm by weight, and Si is controlled to various weight concentrations. As a result, it was best to set Si in the range of 500 to 15000 ppm by weight from the viewpoint of H ₂ O, CO ₂ adsorption and prevention of reduction in discharge delay. That is, if the Si concentration is less than 500 ppm by weight, a sufficient Si oxide film is not formed on the surface of the protective layer, and if it exceeds 15000 ppm by weight, the amount of electron emission decreases and the discharge delay increases.
[0031]
FIG. 5 shows the measurement results of the electron emission characteristics from the protective layer thus prepared. The electron emission characteristic from MgO, which is a conventional protective layer, is 1, and is a relative value with the addition of Ge and Si to the MgO of the present invention. The measurement method of FIG. 5 measures the amount of electric charge flowing through the electrodes arranged in the opposite direction by causing in-plane discharge of a sample in which each MgO film is arranged on the discharge surface. From this result, it can be confirmed that the electron emission amount of the present invention in which the concentration range of Si and Ge is specified is higher than that of the prior art.
[0032]
FIGS. 6 and 7 show the amounts of H ₂ O and CO ₂ adsorbed on the MgO film, respectively. The amount of H ₂ O and CO ₂ adsorbed on MgO, which is a conventional protective layer, is set to 1, and only 300 to 8000 ppm by weight of Ge is added to MgO of the present invention, and 300 to 8000 ppm by weight of Ge and Mg to MgO. Is a relative value to that added with 500 to 15000 ppm by weight. The measuring method is as follows. After forming the protective layers (samples) of the conventional and the present invention, they are allowed to stand for a certain period of time (the time required for production), and these samples are subjected to H ₂ O to each sample by a quadrupole mass spectrometer using temperature programmed desorption. And the amount of CO ₂ adsorption is measured. According to the measurement results of FIGS. 6 and 7, compared with the conventional MgO-only protective layer, the one in which only Ge is added to the MgO of the present invention is not different from the conventional one, but the one in which Ge and Si are added to MgO The amount of adsorption of H ₂ O and CO ₂ is decreasing. This is because a Si oxide film is formed on the MgO surface, and formation of a deteriorated layer by MgO, H ₂ O, and CO ₂ is prevented.
[0033]
From these facts, as the material for the protective layer of the PDP, the addition of Ge to 300 to 8000 ppm by weight and Si to 500 to 15,000 ppm by weight improves the electron emission capability by Ge, and Si is added to the MgO surface. By making a film such as Mg ₂ SiO ₄ or MgSiO ₃ , adsorption of H ₂ O and CO ₂ is prevented. As a result, an image with a small discharge delay and no flicker is generated, and no impurity gas such as H ₂ O and CO ₂ is generated in the discharge space, so that the PDP is prevented from being deteriorated and the life of the PDP is extended.
[0034]
【The invention's effect】
In the method for producing a PDP of the present invention, an electrode constituting a main electrode pair is covered with a discharge gas by an insulating layer, and a protective layer made of an alkaline earth metal oxide covering the insulating layer is disposed, The Ge concentration contained in the raw material for producing the protective layer by vapor deposition is set to a concentration range of 300 to 8000 ppm by weight.
[0035]
By adopting such a Ge concentration range, an impurity level is formed between the valence band and the conduction band, and the electron emission capability is improved. As a result, it is possible to suppress the discharge delay, improve the responsiveness of the occurrence of discharge with respect to voltage application, and have a great effect of displaying a good image.
[0036]
In the present invention, the raw material of the protective layer contains MgO, and contains 300 to 8000 ppm by weight of Ge and 500 to 15000 ppm by weight of Si.
[0037]
Accordingly, the Si oxide film is formed on the surface of the protective layer while suppressing the discharge delay, so that the formation of the altered layer of the protective layer is prevented, which has a great effect of extending the life of the panel.
[Brief description of the drawings]
FIG. 1 is a partial perspective view of an AC surface discharge type PDP according to an embodiment of the present invention. FIG. 2 is a block diagram showing an image display device configured by connecting a drive circuit to the PDP according to the embodiment. FIG. 4 is a time chart showing a driving waveform of the PDP according to the embodiment. FIG. 4 is a diagram showing a change in discharge delay time with respect to Ge concentration in the protective layer according to the embodiment. FIG. FIG. 6 is a diagram showing a comparison of the amount of electron emission from the layer. FIG. 6 is a diagram showing a comparison of the H ₂ O adsorption amount between the embodiment and the conventional protective layer. FIG. It shows a comparison of the ₂ adsorption amount [description of symbols]
11 Front glass substrate 11a Surface 12a Scan electrode 12b Sustain electrode 13 Dielectric glass layer 14 Protective layer 16 Back glass substrate 17 Address electrode 18 Electrode protective layer 19 Partition 20 Phosphor layer 30 Discharge space 220 Address electrode drive unit 230 Scan electrode drive unit 240 Sustain electrode drive part PA1 Front panel PA2 Rear panel

Claims (5)

A method of manufacturing a plasma display panel in which an electrode constituting a main electrode pair is covered with a discharge gas by an insulating layer, and a protective layer made of an alkaline earth metal oxide covering the insulating layer is disposed,
Producing the protective layer by vapor deposition;
And the manufacturing method of the plasma display panel characterized by germanium [Ge] contained in the raw material which produces the said protective layer is the following density | concentration range.
Germanium: 300-8000 ppm by weight   The method for manufacturing a plasma display panel according to claim 1, wherein the protective layer is magnesium oxide [MgO]. 3. The method of manufacturing a plasma display panel according to claim 1 , wherein the raw material contains silicon [Si] in the following concentration range.
Silicon: 500-15000 ppm by weight An electrode constituting the main electrode pair is covered with a discharge gas by an insulating layer, and a raw material for producing a protective layer of a plasma display panel by depositing a protective layer covering the insulating layer by vapor deposition ,
The raw materials, raw materials, characterized in that germanium [Ge] is magnesium oxide in a concentration range of below.
Germanium: 300-8000 ppm by weight The raw material according to claim 4 , wherein the raw material contains silicon [Si] in the following concentration range.
Silicon: 500-15000 ppm by weight

Images