JP2006269258A - Gas discharge display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PDP which can achieve both of shortening an electric discharge lag time and improving an electric discharge probability. <P>SOLUTION: This gas discharge display panel PDP 100 has scan electrodes 102a and data electrodes 112 which are arranged in members opposed to each other with a discharge space in-between, respectively. On the scan electrodes 102a, a dielectric layer 106 and a protection layer 107 are laminated in this order, and discharges occur between the scan electrode 102a and the data electrode 112. The protection layer 107 contains magnesium oxide as a main component, hydrogen atoms and zinc atoms are contained in the magnesium oxide, and a molar ratio of the zinc atoms with respect to the magnesium atoms contained in the magnesium oxide is between 0.02 and 0.12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gas discharge display panel, and more particularly to a technique for improving the discharge accuracy of a plasma display panel.

2. Description of the Related Art In recent years, plasma display panels (hereinafter referred to as “PDP”) in gas discharge display devices used in computers, televisions, and the like have attracted attention as display devices that are large, thin, and lightweight.
This PDP is a gas discharge panel that displays an image by exciting and emitting phosphors with ultraviolet rays generated by gas discharge. PDP can be classified into AC type (AC type) and DC type (DC type) based on the method of forming the discharge. Among them, AC type is superior to DC type in terms of luminance, luminous efficiency and life. It has become the mainstream of the current PDP. (For example, Patent Document 1)
More specifically, the AC type PDP has a configuration in which a front plate and a back plate are opposed to each other and an outer periphery thereof is sealed with a sealing glass.

The front plate has a striped display electrode pair formed on the surface of the front glass substrate, a dielectric layer formed thereon, and a protective layer formed thereon.
The back plate is formed by forming striped data electrodes on the surface of the back glass substrate, forming a dielectric layer thereon, and forming a partition between adjacent data electrodes. A phosphor layer that emits red, green, and blue light is sequentially formed between adjacent barrier ribs.

The back plate and the front plate are arranged so as to face each other so that the electrodes arranged on both sides are orthogonal to each other, and discharge gas is generated in a sealed space formed by sealing the outer edge. Filled.
The display electrode pair is composed of two pairs, one of which is called a scan electrode and the other is called a sustain electrode.

The vicinity of the region where the display electrode pair and one data electrode intersect three-dimensionally across the discharge space is a cell that contributes to image display.
In the AC type PDP, an image 1 field is time-divided into a plurality of subfields, and gradation display is performed by controlling the number of discharges for each subfield.
Each subfield is further divided into periods called an erasing period, an initialization period, a writing period, and a sustaining period, and a process specific to each period is executed in each period.

During the writing period, in the discharge cells to be lit, a negative voltage pulse is sequentially applied from the scanning electrode at the upper end of the panel, and a positive voltage pulse corresponding to the image data on the scanning line is applied to the data electrode. As a result, a so-called write discharge is generated.
Thus, in the discharge cell to be lit, negative wall charges are accumulated on the phosphor layer surface and the protective layer surface near the sustain electrode, and positive wall charges are accumulated on the protective layer surface near the scan electrode.

On the other hand, in the discharge cells that are not lit, no voltage is applied to the data electrodes, so that no write discharge is performed and no wall charges are accumulated.
By the way, in recent years, high definition TV (for example, 1280 × 720) called HDTV (High Definition Television), which has been increased in resolution by increasing the number of scanning lines, has become widespread, and also supports higher definition in PDPs. What to do has appeared.

In the PDP corresponding to such high definition, the number of scan electrodes, sustain electrodes, and data electrodes is remarkably increased, so that the processing amount in the write period, that is, the number of write discharges is increased.
Therefore, in order to complete all the write discharges within one subfield, the application time t1 of each voltage pulse to the scan electrode and the data electrode applied in synchronization in the write period is shortened as shown in FIG. In actuality, however, a time lag (hereinafter referred to as “discharge delay”) occurs between the start of voltage application and the start of discharge. Therefore, the shorter the voltage application time, There is a tendency for the probability of discharge to be low.

As a technique for suppressing the occurrence of such a discharge delay, for example, there is a technique of adding a predetermined amount of hydrogen to the protective layer to shorten the discharge delay time. (For example, Patent Document 2)
JP-A-9-92133 JP 2002-33053 A

However, when hydrogen is added to the protective layer, the secondary electron emission coefficient is increased and the discharge delay time is shortened. On the other hand, the charge tends to move and the wall charge retention ability is lowered. However, there is a problem that electric charges are lost before the discharge contributing to light emission is started, and in some cases, the discharge cannot be performed, that is, a writing failure occurs.
The present invention has been made to solve such a problem, and an object of the present invention is to provide a PDP capable of both reducing the discharge delay time and improving the discharge probability.

  In order to achieve the above object, a gas discharge display panel according to the present invention has a first electrode and a second electrode respectively disposed on members disposed opposite to each other across a discharge space, and the first electrode A dielectric discharge layer and a protective layer are sequentially stacked on the gas discharge display panel for discharging between the first electrode and the second electrode, wherein the protective layer is mainly composed of magnesium oxide, The magnesium oxide contains hydrogen atoms and zinc atoms having a molar ratio of 0.02 or more and 0.12 or less with respect to magnesium atoms contained in the magnesium oxide.

  In order to achieve the above object, a gas discharge display device according to the present invention includes the gas discharge display panel and a drive circuit for driving the display panel.

With the above configuration, the discharge delay time can be shortened while maintaining the charge retention performance as much as possible.
That is, it is possible to achieve both reduction of the discharge delay time and improvement of the discharge probability.
The molar ratio of the hydrogen atoms to all atoms in the protective layer is preferably 0.005 or more and 0.05 or less.

  As a result, the discharge delay time can be shortened to a level compatible with HDTV.

(Embodiment)
(Constitution)
FIG. 1 is a cross-sectional view of a portion corresponding to one pixel of a PDP 100 which is an example of a gas discharge display panel according to an embodiment of the present invention.
The PDP 100 is an alternating current (AC type) PDP that supports high definition, and includes a front plate 90 and a back plate 91 that are disposed with their main surfaces facing each other.

The front plate 90 includes a front glass substrate 101, a display electrode pair 102, a dielectric layer 106, and a protective layer 107.
The front glass substrate 101 is a member serving as a base of the front plate 90, and the display electrode pair 102 is formed on the front glass substrate 101.
One of the display electrode pair 102 is a scan electrode 102a, and the other is a sustain electrode 102b.

The scan electrode 102a has a bus electrode 105a arranged at the edge along the longitudinal direction of a strip-shaped transparent electrode 103a made of a transparent conductive material such as ITO or SnO ₂ .
Further, the scan electrode 102a is formed by arranging a linear bus electrode 105b at an edge along the longitudinal direction of the strip-shaped transparent electrode 103b.
Since the bus electrode 105a and the bus electrode 105b are mainly composed of a highly conductive silver (Ag) thick film, an aluminum (Al) thin film, or a Cr / Cu / Cr laminated thin film, the overall resistance value is lowered. Fulfill.

The display electrode pair 102 and the front glass substrate 101 are further made of low-melting glass (thickness 20 μm to 50 μm) mainly composed of lead oxide (PbO), bismuth oxide (Bi ₂ O ₃ ), or phosphorus oxide (PO ₄ ). A dielectric layer 106 and a protective layer 107 are covered.
This protective layer 107 is a film body based on MgO having an average thickness of about 1.0 μm, and is added with hydrogen and zinc.

More specifically, the molar ratio of hydrogen atoms to all atoms in the protective layer is 0.01, and the molar ratio of zinc atoms to magnesium atoms in the protective layer is 0.03. .
The back plate 91 is a fluorescence formed on the wall surface of the back glass substrate 111, the data electrode 112, the dielectric layer 113, the partition 114, and the gap between the adjacent partitions 114 (hereinafter referred to as “partition groove”). And body layer 115.

As the luminescent material of the phosphor layer 115, for example, a phosphor material as shown below is used.
Green phosphor Zn ₂ SiO ₄ : Mn
Red phosphor Y ₂ O ₃ : Eu
Blue phosphor BaMgAl ₁₀ O ₁₇ : Eu
That is, the phosphor layer 115 includes a green phosphor layer 115G containing the green phosphor, a red phosphor layer 115R containing the red phosphor, and a blue phosphor layer 115B containing the blue phosphor.

The front plate 90 and the back plate 91 are overlapped to face each other and bonded through a sealing glass (not shown) provided on the peripheral portion thereof, and the red phosphor layer 115R, the green phosphor layer G, and the blue fluorescence are joined together. A gap between the body layer B and the protective layer 107 becomes a discharge space 116.
In the discharge space 116, a discharge gas (filled gas) made of a rare gas component such as He, Xe, or Ne is sealed at a pressure of about 500 to 600 Torr (66.5 to 79.8 kPa).

A region in the vicinity where the display electrode pair 102 and one data electrode 112 intersect with each other across the discharge space 116 serves as a discharge cell contributing to image display.
In this PDP 100, after a voltage is applied between the scan electrode crossing the discharge cell to be lit and the data electrode 112 to cause an address discharge, a pulse voltage is applied to the scan electrode 102a and the sustain electrode 102b crossing the discharge cell. As a result, sustain discharge is performed.

In the discharge space 116, ultraviolet light (resonant line having a wavelength of about 147 nm as a central wavelength) is generated by the sustain discharge, and this ultraviolet light is irradiated to the phosphor layer 115, whereby the ultraviolet light is converted into visible light, and the discharge cell. Lights up and an image is displayed.
<Evaluation test>
The inventors conducted the following evaluation tests on PDP 100 in the present embodiment.
1) Discharge delay test 2) Wall charge retention capability test (spec of test product)
(I) Example product: It is the same as the PDP 100 in the embodiment, and specific specifications are shown below.

Protective layer thickness: 1.0 μm
Zn addition amount:
The molar ratio of zinc atoms to magnesium atoms in the protective layer is 0.03
Amount of hydrogen added:
The molar ratio of hydrogen atoms to all atoms in the protective layer is 0.01
(Ii) Conventional product 1: A conventional PDP in which the protective layer is composed of MgO, and specific specifications are shown below.

Protective layer thickness 1.0μm
(Iii) Conventional product 2: This is a conventional PDP having a protective layer in which hydrogen is added to MgO, and specific specifications are shown below.
Protective layer thickness 1.0μm
Amount of hydrogen added The molar ratio of hydrogen atoms to all atoms in the protective layer is 0.01.
1) Outline of the discharge delay test When a voltage was applied to the scan electrode and the data electrode for one discharge cell, the time from the voltage application to the discharge formation was measured.

First, in the conventional product 1 in which hydrogen and zinc were not added to the protective layer, the discharge delay time T ₀ was obtained. Further, the discharge delay times T ₁ and T ₂ were also obtained for other test products (conventional product 2 and example product).
And the wall charge retention ability relative ratio was calculated | required by the following formula | equation.
(Formula 1)
Relative ratio of discharge delay time = T / T ₀ × 100
That is, relative discharge delay times in other test products were obtained with the discharge delay time of the conventional product 1 as a reference.
2) Outline of Wall Charge Retention Capability Test The voltage applied to each discharge cell is determined by the sum of the externally applied voltage and the voltage formed by the wall charge.

In other words, it is considered that the discharge starts when the condition of the discharge start voltage <the externally applied voltage + the voltage formed by the wall charge is satisfied. If the voltage formed by the wall charge is obtained by back calculation, the wall charge is formed. Voltage (V _w ) = discharge start voltage (constant value) −externally applied voltage.
Therefore, the value (V _w ) of the voltage formed by the wall charges can be obtained by measuring the value of the externally applied voltage required for the start of discharge.

First, in the conventional product 1 in which hydrogen and zinc were not added to the protective layer, a voltage value V _w0 formed by wall charges was obtained. In addition, the voltage values V _w1 and V _w2 formed by the wall charges were also obtained for the PDPs of other test products (conventional product 2 and example product).
And the wall charge retention ability relative ratio was calculated | required by the following formula | equation.
(Formula 2)
Wall charge retention capacity relative ratio = V _w / V _w0 × 100
That is, the relative wall charge holding ability of other test products was determined based on the wall charge holding ability of the conventional product 1.
(Test results)
1) The results of the discharge delay test will be described below.

FIG. 2 is a diagram showing a relative reduction rate of the discharge delay time of each test product when the discharge delay time of the protective layer of the conventional product 1 is 100%.
From this result, the discharge delay time of the conventional product 2 is shortened to 60% of the conventional product 1.
Further, in the example product, the discharge delay time is shortened to 72% of the conventional product 1.
With the increase in display definition, the discharge delay time required for the product is preferably shortened. In this case, it is desirable to maintain 60% to 80%, which is the same level as the conventional product 2. .

2) The results of the wall charge holding ability test will be described below.
FIG. 3 is a diagram showing the relative ratio of the wall charge retention ability of the conventional product 1, the conventional product 2, and the example product.
In the protective layer of the conventional product 2 to which only hydrogen is added, the wall charge retention capacity relative ratio is 46.8%, whereas in the protective layer of the example product to which zinc is further added, it is significantly increased to 77.3%. I understand that

When the value of the relative ratio of the wall charge retention capacity becomes small, the externally applied voltage becomes high, and since the probability that the cell to be lit does not light up becomes high, there is a lower limit value allowed as a product specification. Here, the lower limit is set to 70%.
Therefore, the conventional product 2 in which hydrogen is simply added to the protective layer is below this lower limit value, but the example product in which hydrogen and zinc are added to the protective layer is above this lower limit and has no problem. It has become.
(Additional test)
The inventors of the present invention realize a protective layer in which the suppression of discharge delay and the securing of wall charge retention capability are compatible in the protective layer in which the molar ratio of hydrogen to all atoms is 0.01 or more and 0.05 or less. Above, additional tests were performed to determine the appropriate amount of zinc added.

In addition, for the measurement of the amount of zinc contained in the protective layers of the conventional products 1 and 2 and the examples, the CIROS 120 manufactured by Rigaku was used as a measuring device, and the liquid obtained by dissolving the protective layer with nitric acid was used. Analysis was performed by ICP emission spectroscopy.
As a result, it was found that when the molar ratio of zinc to magnesium contained in the protective layer satisfies the following conditions, it is possible to achieve both suppression of discharge delay and securing of wall charge retention capability.

(conditions)
The molar ratio of zinc atoms to magnesium atoms contained in the protective layer is from 0.02 to 0.12.
When the amount of zinc added to the protective layer was less than the lower limit of the above conditions, the wall charge retention capability was low, and the probability of occurrence of write failure increased rapidly.
(Attachment 1)
The inventors changed the amount of hydrogen contained in the protective layer in various ways and determined the relationship between the hydrogen content in the protective layer and the discharge delay.

In addition, in order to measure the amount of hydrogen contained in the protective layers of the conventional products 1 and 2 and the example products, hydrogen forward scattering (HFS) was analyzed using a hydrogen forward scattering method (HFS).
As a result, in order to shorten the discharge delay time to a level that can cope with high definition, the hydrogen atoms to be added to the protective layer have a molar ratio of 0.005 to all atoms contained in the protective layer. It turns out that this is necessary.

Further, when the amount of hydrogen added to the protective layer is large, the crystallinity of MgO is deteriorated, so that the discharge characteristics are deteriorated. Therefore, it was found that the molar ratio of hydrogen to all atoms in the protective layer is preferably 0.05 or less.
(Attachment 2)
In recent years, there is a tendency to increase the partial pressure of xenon in the discharge gas in order to improve the light emission efficiency of the discharge display panel. As the xenon partial pressure increases, secondary electron emission is promoted, but the charge retention performance tends to decrease. Therefore, by adding zinc to the protective layer, the secondary electron emission performance is suppressed. The use is expected more and more.

In consideration of such a situation, the inventors sought for an amount of zinc to be added that enables both suppression of discharge delay and securing of charge retention performance when the partial pressure of xenon contained in the discharge gas is high. The test was conducted.
As a result, it has been found that when the xenon partial pressure in the discharge gas is 15 mol%, the molar ratio of zinc to magnesium is preferably 0.02 or more and 0.05 or less.

<Method of Forming Protective Layer 107 on Dielectric Layer 106>
In this embodiment, a method for forming the protective layer 107 over the dielectric layer 106 is described.

First, the scan electrode 102a and the sustain electrode 102b are formed on the front glass substrate 101, and then the dielectric layer 106 is formed using a screen printing method, a die coat printing method, or a sheet laminating method, and then an electron beam evaporation method is performed. A protective layer 107 is formed on the dielectric layer 106 using the protective layer 107.
As a deposition source used for forming the protective layer, for example, a pellet-like MgO mixed with a pellet-like or powdered zinc compound, or a mixture of powdered MgO and a powdered zinc compound, Alternatively, by using a sintered body of the mixture and adjusting the mixing ratio of the zinc compound, the molar ratio of zinc atoms to magnesium atoms of MgO, which is the main material of the protective layer, is 0.02 or more and 0.12 or less. To.

Further, hydrogen is adjusted in the atmosphere during vapor deposition so that the hydrogen concentration in the protective layer becomes a target value.
Thus, the protective layer 107 containing MgO as a main component and zinc and hydrogen mixed at a predetermined ratio can be formed.
Considering that the melting points of MgO and zinc compound are different, electron beam evaporation may be performed using two kinds of evaporation sources of MgO and zinc compound in order to realize a predetermined ratio more precisely.

In order to control the hydrogenation rate more precisely, a material obtained by mixing a magnesium compound such as magnesium hydroxide and MgO at a predetermined ratio may be used as a deposition source.
In order to control the hydrogenation rate more precisely, an MgO film to which zinc is added may be formed, and then the plasma treatment may be performed on the film in an atmosphere containing hydrogen.
Further, in order to control the hydrogenation rate more precisely, the deposition source mixed with the zinc compound is heated by an electron beam gun while irradiating the substrate with hydrogen ions from an ion gun connected to a hydrogen cylinder. Also by this method, a protective layer containing hydrogen and zinc can be formed.

  Note that as a method for forming the protective layer 107, not only an electron beam evaporation method but also a sputtering method (including a reactive sputtering method) or an ion plating method can be used. Also in this case, the protective layer 107 in which zinc and hydrogen are mixed at a predetermined ratio can be formed by controlling the mixing ratio of the constituent materials of the target or the evaporation source and the gas atmosphere at the time of formation.

  In this embodiment, the discharge gas composed of rare gas components such as He, Xe, and Ne is enclosed. However, the discharge gas is not limited to the mixed gas of neon and xenon, but helium or krypton. You may use it, for example by mixing noble gases.

  The present invention is applicable to display devices used for televisions, computer monitors, and the like.

It is sectional drawing of the part corresponding to 1 pixel of PDP which is an example of the gas discharge display panel in embodiment of this invention. It is a figure which shows the result of the discharge delay test in embodiment of this invention. It is a figure which shows the result of the wall charge retention ability test in embodiment of this invention. It is a figure which shows the drive voltage application pattern in the conventional PDP.

Explanation of symbols

90 Front plate 91 Back plate 100 PDP
DESCRIPTION OF SYMBOLS 101 Front glass substrate 102 Display electrode pair 102a Scan electrode 102b Sustain electrode 103a Transparent electrode 103b Transparent electrode 105a Bus electrode 105b Bus electrode 106 Dielectric layer 107 Protective layer 111 Back glass substrate 112 Data electrode 113 Dielectric layer 114 Bulkhead 115 Phosphor layer 115 Blue phosphor layer 115 Red phosphor layer 115 Green phosphor layer 116 Discharge space

Claims (3)

A first electrode and a second electrode disposed on a member disposed opposite to each other across the discharge space, and a dielectric layer and a protective layer are sequentially stacked on the first electrode; A gas discharge display panel that discharges between an electrode and the second electrode,
The protective layer is composed mainly of magnesium oxide,
A gas discharge display panel comprising, in the magnesium oxide, a zinc atom having a molar ratio of 0.02 or more and 0.12 or less to a magnesium atom contained in the magnesium oxide and a hydrogen atom.   The gas discharge display panel according to claim 1, wherein a molar ratio of the hydrogen atoms to all atoms in the protective layer is 0.005 or more and 0.05 or less.   A gas discharge display device comprising the gas discharge display panel according to claim 1 and a drive circuit for driving the display panel.

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