WO2010122730A1 - Plasma display panel and method for manufacturing same - Google Patents

Abstract

Provided is a PDP wherein a discharge delay and a discharge start voltage are suppressed by improving the discharge characteristics of a protection layer and excellent image display performance can be exhibited with a highly fine cell structure. On the surface of a dielectric layer (7) of a front panel (2), a MgO layer (8) is disposed, and on the surface of the MgO layer (8), a first electron emitting material (16a), which is composed of MgO fine particles containing halogen atoms, and a second electron emitting material (16b), which is composed of fine particles of a compound having one or more kinds of elements selected from among Ca, Sr and Ba, and Sn as the main component, are dispersed. A protection layer (17) is composed of the MgO layer (8), the dispersed first electron emitting material (16a) and the dispersed second electron emitting material (16b).

Description

Plasma display panel and manufacturing method thereof

The present invention relates to a plasma display panel, and more particularly to an AC type plasma display panel.

Plasma display panels (hereinafter referred to as PDPs) are capable of high-speed display among flat panel displays (FPDs) and are easy to increase in size, so they are widely put into practical use in fields such as video display devices and public information display devices. Has been.

FIG. 4 is a diagram schematically showing the structure of a discharge cell in a general AC type PDP.

The PDP 1x shown in FIG. 4 is configured by pasting the front panel 2 and the back panel 9 together.

In the front panel 2, a plurality of display electrode pairs 6 each including the scanning electrode 5 and the sustain electrode 4 are disposed over one side of the front panel glass 3, and the dielectric layer 7 covers the display electrode pair 6. And the MgO layer 8 are sequentially laminated. The scan electrode 5 and the sustain electrode 4 are configured by laminating transparent electrodes 51 and 41 and bus lines 52 and 42, respectively.

The dielectric layer 7 is formed of a low melting point glass having a glass softening point in the range of about 550 ° C. to 600 ° C., and has a current limiting function peculiar to the AC type PDP.

The MgO layer 8 is an example of a metal oxide layer, which protects the dielectric layer 7 and the display electrode pair 6 from plasma collision ion collisions, efficiently emits secondary electrons, and lowers the discharge start voltage. To play a role. Usually, the MgO layer 8 is made of MgO having excellent secondary electron emission characteristics, sputtering resistance, and optical transparency by a thickness of 0.5 μm or more by a vacuum deposition method (Patent Documents 1 and 2) or a printing method (Patent Document 3). It is formed by forming a film with a thickness of about 1 μm.

In the back panel 9, a plurality of data (address) electrodes 11 for writing image data are provided on the back panel glass 10, and a dielectric layer 12 made of low-melting glass is disposed so as to cover the data electrodes 11. In the dielectric layer 12, on the boundary between adjacent discharge cells, a partition wall (rib) 13 having a predetermined height made of low-melting glass separates the discharge space 15 so as to form a pattern portion 1231 having a grid pattern or the like. , 1232 and phosphor layers 14 ( phosphor layers 14R, 14G, 14B) formed by applying and firing phosphor inks of R, G, B colors on the surface of the dielectric layer 12 and the side surfaces of the barrier ribs 13. ) Is formed.

The front panel 2 and the back panel 9 are arranged such that the display electrode pair 6 and the data electrode 11 are orthogonal to each other via the discharge space 15, and each periphery thereof is sealed and sealed internally. The discharge space 15 is filled with a rare gas such as Xe—Ne or Xe—He as a discharge gas at a pressure of about several tens of kPa.

In order to display an image on such a PDP, a gradation expression method (for example, an intra-field time division display method) that divides an image of one field into a plurality of subfields (SF) is used.

In recent years, there has been a demand for higher definition (full-spec high-definition TV, etc.) and higher speed driving of PDPs, and in response to this, extensive research has been conducted to improve the discharge characteristics of PDPs, especially to prevent “discharge delay”.・ Suppression is listed as an important issue.

“Discharge delay” refers to a phenomenon in which discharge occurs after the application of a pulse voltage. When “discharge delay” becomes prominent, the probability of completion of discharge within the applied pulse width decreases, and the lamp is originally lit. A lighting failure occurs because writing cannot be performed in the power cell. In particular, when high-speed driving is performed by narrowing the width of the driving pulse, or in a high-definition cell structure, such a lighting failure due to a discharge delay is particularly apparent.

The cause of “discharge delay” is considered to be mainly due to the characteristics of the protective layer. At present, MgO, which is the main material of the protective layer, is doped with elements such as Fe, Cr, V, Si, Al, etc. Attempts have been made to improve the discharge characteristics of the protective layer by adding the dopant (Patent Documents 1 and 2).

On the other hand, the protective layer is formed by arranging the MgO single crystal fine particles produced by the vapor phase oxidation method in a layer form directly on the dielectric layer or on the MgO film produced by the thin film method. Attempts have also been made to improve the surface discharge characteristics (Patent Document 3). According to the method of Patent Document 3, it is said that a certain improvement can be achieved with respect to reduction of discharge delay at low temperatures.

Further, in the PDP, high efficiency is also strongly demanded, and as a means for solving this, a method of reducing the dielectric constant of the dielectric layer and a method of increasing the Xe partial pressure of the discharge gas are known. However, when such a means is used, there is a problem that the discharge start voltage and the sustain voltage increase.

On the other hand, it is known that if a material having a high secondary electron emission coefficient is used for the protective layer, it is possible to lower the discharge start voltage and the sustain voltage, thereby achieving high efficiency. Since an element having a low withstand voltage can be used for the drive circuit, cost reduction can be realized. Therefore, as a protective layer material having a high secondary electron emission coefficient, the same alkaline earth metal oxide as MgO is used, but CaO, SrO, BaO having a higher secondary electron emission coefficient is used, or a solid solution of these. (Patent Documents 6 to 7).

JP-A-8-236028 JP-A-10-334809 JP 2006-173018 A JP 2006-147417 A JP-A-64-28273 JP-A-52-63663 JP 2007-95436 A

However, it cannot be said that the prior art described in any of the above-mentioned patent documents has sufficiently obtained the effect of reducing the discharge delay, the discharge start voltage, and the sustain voltage.

For example, Patent Document 3 uses MgO fine particles (powder) produced by a gas phase oxidation method, but the particles produced by the gas phase oxidation method have a relatively varied particle size. A large number of fine particles are contained for large particles. Such a large number of fine particles contain fine particles that do not substantially contribute to prevention / suppression of discharge delay. Therefore, a practical discharge delay suppressing effect cannot be obtained unless a relatively large amount of MgO fine particles are dispersed in the PDP. On the other hand, if a large amount of MgO fine particles are disposed on the dielectric layer or the MgO layer, the visible light generated by the phosphor is scattered and the visible light transmittance is reduced.

In order to solve these problems, a method of removing MgO fine particles having a small particle diameter by classification has been proposed (Patent Document 4). However, in that case, it is necessary to perform a new classification process, which increases the number of processes and lowers the production efficiency, and also requires a large classification apparatus. Furthermore, various problems in terms of manufacturing costs occur in industrial production such as generation of useless MgO materials that cannot be used after the classification process.

In addition, CaO, SrO, BaO and the like studied in Patent Documents 6 to 7 are chemically unstable as compared with MgO, and easily react with moisture and carbon dioxide in the air to generate hydroxide and Form carbonates. When such a compound is formed, the secondary electron emission coefficient decreases, and the expected voltage reduction effect cannot be obtained, or the aging time required for voltage reduction becomes very long, which is practical. There is a problem of disappearing.

Degradation due to such chemical reactions can be avoided by controlling the atmosphere gas of the work when producing a small amount at the laboratory level, but it is difficult to control the atmosphere of all processes at the manufacturing plant. Yes, even if possible, it leads to higher costs.

As described above, a technology that can sufficiently reduce the discharge delay and driving voltage of the PDP and can be used industrially has not been established.

Furthermore, for any of the above characteristics of the discharge delay and the driving voltage, it is desired that the characteristic fluctuation is small when the PDP is displayed for a long time. In particular, when high-speed driving is performed in a high-definition cell structure such as full HD, these characteristics change over time, which is a problem to be solved.

In order to solve the above-described problems, the present invention is configured such that a first substrate including an electrode and a dielectric layer is disposed to face a second substrate through a discharge space, and the periphery of both the first and second substrates is sealed. In the PDP, on the surface of the first substrate on the first dielectric layer side, the first material made of MgO fine particles containing halogen atoms so as to face the discharge space, and one kind selected from Ca, Sr, and Ba The second material composed of fine particles of a compound containing Sn as a main component was present.

Here, a metal oxide layer mainly composed of MgO is provided on the discharge space side of the dielectric layer, and the first material and the second material are disposed on the discharge space side of the metal oxide layer. Good.

Halogen atoms are preferably contained in the vicinity of the surface layer of the MgO fine particles.

As the halogen atom, a fluorine atom or a chlorine atom can be used.
As the compound constituting the second material, a crystalline oxide containing one or more selected from Ca, Sr, and Ba and Sn in a specific ratio is preferable.

In particular, one or more crystalline compounds selected from CaSnO ₃ , SrSnO ₃ , BaSnO ₃ , or a solid solution in which these are solid-solved with each other are preferable.

The coverage with which the fine particles constituting the first material and the second material cover the dielectric layer is preferably 1.0% or more and 50% or less in projected area ratio.

In the method for manufacturing a PDP according to the present invention, a metal oxide layer forming step of forming a metal oxide layer on the surface of the dielectric layer on the first substrate on which the electrode and the dielectric layer are disposed, A sealing step is provided in which the first substrate on which the oxide layer is formed and the second substrate are disposed opposite to each other and sealed, and the metal oxide layer is formed between the metal oxide forming step and the sealing step. A step of disposing a first material and a second material on the surface is provided. As the first material, magnesium fluoride, magnesium chloride, aluminum fluoride, calcium fluoride, fluoride are applied to the MgO precursor. Using MgO fine particles obtained by firing a material obtained by adding at least one selected from lithium, magnesium chloride, aluminum chloride, calcium chloride, lithium chloride, and sodium chloride as a sintering aid, material To, Ca, Sr, one or more selected from Ba, and we decided to use the particulate compound mainly containing Sn.

In the step of disposing the first material and the second material, it is preferable to dispose the first material on the surface of the metal oxide layer and then dispose the second material.

According to the PDP of the present invention, the first material composed of MgO fine particles containing a halogen atom, the second material composed of fine particles of a compound mainly composed of Sn, one or more selected from Ca, Sr, and Ba. Both of these materials have a high secondary electron emission coefficient γ, and these are arranged so as to face the discharge space on the surface of the dielectric layer. Therefore, when the PDP is driven, 2 is directed toward the discharge space. Secondary electrons are abundantly emitted. Therefore, compared with the conventional PDP, the discharge delay is suppressed and the driving can be performed at a low voltage.

Further, according to the PDP of the present invention, the discharge delay reduction effect and the reduction effect are maintained for a long time. In addition to the excellent stability of the second material, this is an effect based on the interaction by disposing different types of the first material and the second material. Further, the discharge delay reduction effect and the drive voltage reduction effect can be obtained without setting the coverage ratios of the first material and the second material to the MgO layer or the dielectric layer so high.

Also, the PDP manufactured by the manufacturing method of the present invention has the same effect.

Therefore, according to the present invention, an excellent image display performance can be exhibited even during high-speed driving due to a discharge delay suppressing effect, and a driving voltage reduction effect can also be obtained.

It is sectional drawing which shows the structure of PDP which concerns on embodiment of this invention. It is a schematic diagram which shows the relationship between each electrode and a driver. It is a figure which shows the drive waveform example of PDP. It is a figure which shows the structure of the conventional general PDP. It is a characteristic view which shows the result of having measured the discharge delay time about each PDP which concerns on an Example and a comparative example. It is a characteristic view which shows the result of having measured the discharge start voltage about each PDP which concerns on an Example and a comparative example.

Hereinafter, embodiments and examples of the present invention will be described, but the present invention is naturally not limited to these forms, and may be appropriately modified and implemented without departing from the technical scope of the present invention. Can do.

(Configuration of PDP)
The overall configuration of the PDP 1 according to the embodiment is the same as that of the PDP 1x shown in FIG. 4 except for the configuration around the protective layer.

FIG. 1 is a schematic cross-sectional view (a cross-sectional view along the XZ plane of FIG. 4) of the PDP 1 according to the embodiment.

In addition, in FIG. 1, the 1st electron emission material 16a and the 2nd electron emission material 16b which are arrange | positioned on the surface of the MgO layer 8 are typically shown larger than actual for description.

As shown in FIG. 1, the PDP 1 is broadly divided into a first substrate (front panel 2) and a second substrate (back panel 9) that are disposed with their main surfaces facing each other.

A front panel glass 3 serving as a substrate of the front panel 2 has a display electrode pair 6 (scanning electrode 5 and sustaining electrode 4) extending in the Y direction with a predetermined discharge gap on one main surface thereof in the X direction. A plurality of pairs are formed side by side. Each display electrode pair 6 includes a strip-shaped transparent electrode 51, 41 made of a transparent conductive material such as indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO ₂ ), an Ag thick film, an Al thin film, Alternatively, bus lines 52 and 42 made of a Cr / Cu / Cr laminated thin film or the like are laminated, and the sheet resistance of the display electrode pair 6 is lowered by the bus lines 52 and 42.

Here, the “thick film” means a film formed by various thick film methods formed by applying a paste containing a conductive material and baking it. On the other hand, the “thin film” refers to a film formed by various thin film methods using a vacuum process, including a sputtering method, an ion plating method, an electron beam evaporation method, and the like.

The front panel glass 3 provided with the display electrode pair 6 has a low melting point glass mainly composed of lead oxide (PbO), bismuth oxide (Bi ₂ O ₃ ) or phosphorus oxide (PO ₄ ) over the entire main surface. The dielectric layer 7 is formed by a screen printing method or the like.

The dielectric layer 7 has a current limiting function peculiar to the AC type PDP, and is an element that realizes a longer life than the DC type PDP.

An MgO layer 8 is formed on the surface of the dielectric layer 7 in the front panel 2, and the first electron emitting material 16a and the second electron emitting material 16b are formed on the surface of the MgO layer 8 so as to face the discharge space. Existing. As will be described in detail later, the first electron emission material 16a is made of MgO fine particles containing halogen atoms, and the second electron emission material 16b is composed mainly of one or more selected from Ca, Sr, and Ba and Sn. Fine particles made of the compound

A protective layer 17 that protects the dielectric layer 7 is constituted by the MgO layer 8 and the first electron emission material 16a and the second electron emission material 16b.

The MgO layer 8 protects the dielectric layer 7 and the display electrode pair 6 from ion collision of plasma discharge, efficiently emits secondary electrons, and lowers the discharge start voltage. It is a thin film formed of MgO having an excellent electron emission coefficient γ and good optical transparency and electrical insulation.

A back panel glass 10 serving as a substrate of the back panel 9 has a data electrode 11 made of any one of an Ag thick film, an Al thin film, a Cr / Cu / Cr laminated thin film, etc. on one main surface, extending in the X direction. As the direction, they are arranged in parallel in the Y direction at regular intervals. A dielectric layer 12 is disposed over the entire surface of the back panel glass 9 so as to enclose each data electrode 11.

On the dielectric layer 12, a grid-like partition wall 13 is further arranged in accordance with the gap between adjacent data electrodes 11, and serves to prevent erroneous discharge and optical crosstalk by partitioning the discharge cells. Yes.

A phosphor layer 14 corresponding to each of red (R), green (G), and blue (B) for color display is provided on the side surface of two adjacent barrier ribs 13 and the surface of the dielectric layer 12 therebetween. Is formed. As various compositions, the blue phosphor (B) has a known BAM: Eu, the red phosphor (R) has (Y, Gd) BO ₃ : Eu, Y ₂ O ₃ : Eu, etc. ) May be Zn ₂ SiO ₄ : Mn, YBO ₃ : Tb, (Y, Gd) BO ₃ : Tb, or the like.

The dielectric layer 12 is not essential, and the data electrode 11 may be directly included in the phosphor layer 14.

The front panel 2 and the back panel 9 are arranged to face each other so that the longitudinal directions of the data electrode 11 and the display electrode pair 6 are orthogonal to each other, and the outer peripheral edge portions of both the panels 2 and 9 are sealed with glass frit. A discharge gas composed of an inert gas component containing He, Xe, Ne or the like is sealed between the panels 2 and 9 at a predetermined pressure.

A discharge space 15 is formed between the barrier ribs 13, and a region where the display electrode pair 6 and one data electrode 11 intersect with each other across the discharge space 15 is a discharge cell (also referred to as “sub-pixel”) for image display. Correspond. One discharge pixel is composed of three discharge cells corresponding to adjacent RGB colors.

Scan electrode driver 111, sustain electrode driver 112, and data electrode driver 113 are electrically connected to each of scan electrode 5, sustain electrode 4 and data electrode 11 as drive circuits in the vicinity of the end in the panel XY direction as shown in FIG. Connected to. Here, sustain electrodes 4 are collectively connected to sustain electrode driver 112, and each scan electrode 5 and each data electrode 11 are independently connected to scan electrode driver 111 or data electrode driver 113, respectively.

(PDP drive example)
The PDP 1 is applied with an AC voltage of several tens of kHz to several hundreds of kHz between the display electrode pairs 6 during driving by a known driving circuit (not shown) including the drivers 111 to 113. As a result, a discharge is generated in an arbitrary discharge cell, and ultraviolet rays (dotted line and arrow in FIG. 1) including a resonance line mainly composed of a wavelength of 147 nm due to excited Xe atoms and a molecular line mainly composed of a wavelength of 172 nm due to excited Xe molecules are phosphor layer 14. Is irradiated. The phosphor layer 14 is excited to emit visible light. The visible light passes through the front panel 2 and is emitted to the front surface.

As an example of this driving method, an in-field time division gradation display method is adopted. In this method, the field is divided into a plurality of subfields (SF), and each subfield is further divided into a plurality of periods.

That is, each subfield has (1) an initialization period in which the wall charges of all the discharge cells are reset by an initialization pulse, and (2) addresses the discharge cells to be lit corresponding to the input data. Write period for accumulating wall charges, (3) sustain period for causing the addressed discharge cells to emit light by applying an alternating voltage (sustain voltage) to all the discharge cells simultaneously, and (4) sustain discharge. Is divided into four periods, ie, an erasing period for erasing the wall charges formed.

FIG. 3 shows an example of drive waveforms in the mth subfield in the field. As shown in FIG. 3, an initialization period, an address period, a sustain period, and an erase period are assigned to each subfield.

In the initialization period, the wall charge of the entire screen is erased (initialization discharge) in order to prevent the influence of the previous discharge cell lighting (effect of accumulated wall charge). Specifically, a voltage (initialization pulse) higher than that of the data electrode 11 and the sustain electrode 4 is applied to the scan electrode 5 to discharge the gas in the discharge cell. The charges generated thereby are accumulated on the wall of the discharge cell so as to cancel the potential difference between the data electrode 11, the scan electrode 5 and the sustain electrode 4, so that the MgO layer 8 and the first electron emission material 16a near the scan electrode 5 Negative charges are accumulated as wall charges on the surface of the second electron emission material 16b. Further, positive charges are accumulated as wall charges on the surface of the phosphor layer 14 near the data electrode 11 and on the surface of the MgO layer 8 near the sustain electrode 4 and the first electron emission material 16a and the second electron emission material 16b. Due to this wall charge, a predetermined wall potential is generated between scan electrode 5 and data electrode 11 and between scan electrode 5 and sustain electrode 4.

In the address period (writing period), addressing (setting of lighting / non-lighting) of the discharge cell selected based on the image signal divided into subfields is performed. In this period, when the discharge cell is turned on, a voltage (scanning pulse) lower than that of the data electrode 11 and the sustain electrode 4 is applied to the scanning electrode 5. That is, a voltage having the same polarity as the wall potential is applied to scan electrode 5 -data electrode 11, and a data pulse having the same polarity as the wall potential is applied between scan electrode 5 and sustain electrode 4, thereby address discharge (writing Discharge). Thereby, negative charges are accumulated on the surface of the phosphor layer 14, the MgO layer 8 near the sustain electrode 4, and the surfaces of the first electron emission material 16 a and the second electron emission material 16 b, and the MgO layer near the scan electrode 5. 8, positive charges are accumulated as wall charges on the surfaces of the first electron-emitting material 16a and the second electron-emitting material 16b. Thus, a predetermined wall potential is generated between sustain electrode 4 and scan electrode 5.

During the sustain period, the discharge is maintained in the discharge cells that have been addressed and discharged in order to ensure the luminance corresponding to the gradation. Here, a voltage pulse for sustain discharge (for example, a rectangular wave voltage of about 200 V) is applied to scan electrode 5 and sustain electrode 4 in different phases. Thereby, in the written discharge cell, a pulse discharge is generated every time the voltage polarity changes.

This sustain discharge emits a resonance line of 147 nm from the excited Xe atoms in the discharge space and a molecular beam mainly composed of 173 nm from the excited Xe molecules. The surface of the phosphor layer 14 is irradiated with the resonance line / molecular beam, and display light is emitted by visible light emission. Then, multi-color / multi-tone display is performed by a combination of sub-field units of RGB colors. In a non-discharge cell in which wall charges are not written, no sustain discharge occurs and the display state is black.

In the erasing period, wall charges are erased by applying a gradual erasing pulse to the scanning electrode 5.
(Configuration of protective layer 17)
The protective layer 17 in the PDP 1 is composed of an MgO layer 8 laminated on the dielectric layer 7, and a first electron emission material 16a and a second electron emission material 16b disposed thereon.

The MgO layer 8 is a thin film formed of an MgO material, and is formed on the dielectric layer 7 by a known thin film forming method such as a vacuum deposition method or an ion plating method. The material of the MgO layer 8 is not limited to MgO but may include other metal oxides containing MgO as a main component.

(First electron emitting material 16a)
The first electron emission material 16a has a configuration in which halogen atoms are included in the vicinity of the surface of MgO fine particles having a uniform particle size distribution. The aspect containing a halogen atom is considered that, for example, a part of the halogen atom is replaced with an oxygen atom, whereby the crystal structure of MgX ₂ (X = halogen element) is partially mixed in the crystal structure of MgO. It is done. Such halogen atoms are mainly contained in the vicinity of the surface of each MgO fine particle, specifically, in a range of 4 nm or less from the surface toward the inside of the particle.

In MgO fine particles, the site involved in the discharge characteristics can be considered only near the surface, so it is important to contain halogen atoms near the surface.

Thus, the MgO fine particles containing halogen atoms in the vicinity of the surface can be obtained by firing a mixed powder obtained by mixing an MgO precursor and a sintering aid. As the MgO precursor, one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium alkoxide, magnesium nitrate, and magnesium acetate can be used.

As a sintering aid, one of halogen compounds such as magnesium fluoride, magnesium chloride, aluminum fluoride, calcium fluoride, lithium fluoride, magnesium chloride, aluminum chloride, calcium chloride, lithium chloride, sodium chloride, etc. The above can be used. In addition, when elements other than magnesium are contained as a residual element after firing, depending on the element type, the discharge characteristics are affected, so the sintering aid can be properly used.

The raw material may be mixed by either wet mixing using a solvent or dry mixing in which a dry powder is mixed.

When performing wet mixing, in addition to water, alcohol such as ethyl alcohol, methyl alcohol, iso-propyl alcohol, n-propyl alcohol, n-butoxy alcohol, sec-butoxy alcohol, tert-butoxy alcohol, or acetic acid is used as a solvent. Acetic esters such as butyl, ethyl acetate, methyl acetate, and 2-methoxyethyl acetate, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone can be used, and are not particularly limited. When performing dry mixing, a ball mill, a medium stirring mill, a planetary ball mill, a vibration mill, a jet mill, a V-type mixer, and the like that are generally used in industry can be used.

The first electron-emitting material 16a is obtained by firing the mixed powder of MgO precursor and sintering aid at 600 ° C. to 1800 ° C., preferably 900 ° C. to 1500 ° C. for 15 minutes to 10 hours.

The firing temperature and firing time are appropriately adjusted according to various conditions such as the particle size and classification conditions of the precursor used, the amount of sintering aid added, and the amount of mixed powder. In order to obtain desired discharge characteristics, the firing atmosphere can be performed in an oxidizing or reducing atmosphere. Depending on the amount of the fired powder, it is preferable to go through a calcination step before the main firing in order to increase the homogeneity of mixing with the sintering aid.

The calcination step is performed, for example, by baking at 700 to 1000 ° C. for 15 minutes to 5 hours in the atmosphere. As in the main calcination step, the calcination temperature and the calcination time are appropriately adjusted according to the difference in conditions as described above. To do. The powder obtained by the calcining step is pulverized and mixed, and then processed in the main baking step. The mixing method of the calcined powder at this time may be either wet mixing or dry mixing. However, in the case of wet mixing, a solvent accompanying dissolution of MgO, such as water, cannot be used. As a firing furnace used in each firing step, a furnace generally used in industry, for example, a continuous type such as a pusher furnace, a batch type electric furnace, a gas furnace, or the like can be used.

Furthermore, the first electron-emitting material 16a obtained in the main firing step can be crushed again using a ball mill, a jet mill or the like, and the particle size distribution and fluidity can be adjusted.

In addition, if there is excessive gas flow in the atmosphere in the firing furnace in the firing process, including main firing and temporary firing, the halogen component added to the sintering aid will be burned out together with the flow gas, resulting in the final production In some cases, the halogen concentration in the MgO fine particles, which is a product, decreases. Such a decrease in the halogen concentration hinders the adjustment of the halogen concentration on the surface of the MgO fine particles. Accordingly, for example, it is desirable to take measures such as putting a material component in a high-purity alumina crucible and applying a suitable sealing measure such as covering and performing a firing step in a firing furnace.

(Second electron emitting material 16b)
The second electron-emitting material 16b is made of a compound containing at least one of Ca, Sr, and Ba and Sn and O as main components.

This compound may be in an amorphous state, but is preferably a crystalline compound in order to further improve the stability.

Basically preferred crystalline compounds include the following.

(1) CaSnO ₃ , SrSnO ₃ , BaSnO ₃ , or a solid solution in which two or more of these are mutually dissolved [(Ca, Sr) SnO ₃ , (Sr, Ba) SnO ₃ etc.].

(2) Sr ₃ Sn ₂ O ₇ , Ba ₃ Sn ₂ O ₇ , or a solid solution in which these are solid-solved with each other [(Sr, Ba) ₃ Sn ₂ O ₇ ].

(3) Ca ₂ SnO ₄ , Sr ₂ SnO ₄ , Ba ₂ SnO ₄ , or a solid solution in which two or more of these are solid-solved with each other [(Ca, Sr) ₂ SnO ₄ etc.]
Comparing the secondary electron emission efficiency among these crystalline compounds, the compound containing SrO has higher secondary electron emission efficiency than the compound containing CaO in the composition, and BaO is higher than the compound containing SrO. The containing compound has higher secondary electron emission efficiency.

Moreover, if it is a compound which contains the same BaO in a composition, the one where the content is large is considered that secondary electron emission efficiency is high. For example, Ba ₃ Sn ₂ O ₇ has higher secondary electron emission efficiency than BaSnO ₃ , and Ba ₂ SnO ₄ has higher secondary electron emission efficiency.

On the other hand, the reverse is true for chemical stability.

Since the required chemical stability varies depending on the process conditions for actually producing PDP, it is difficult to generally decide which compound is good. Among these compounds, CaSnO ₃ , SrSnO ₃ BaSnO ₃ is the most desirable because it is a compound that is as stable as MgO and can be used without any particular atmosphere control and has higher electron emission efficiency than MgO.

However, in the PDP manufacturing process, compounds having other compositions can be used as long as the atmosphere can be controlled to some extent, and in this case, compounds having an appropriate composition may be used according to the environment.

As a method for synthesizing a compound mainly composed of Sn and O and any one or more of Ca, Sr, and Ba, there are a solid phase method, a liquid phase method, and a gas phase method as its form.

The solid phase method is a method in which raw material powders (metal oxide, metal carbonate, etc.) containing each metal are mixed and heat-treated at a temperature of a certain level or more to react.

In the liquid phase method, a solution containing each metal is prepared, and a solid phase is precipitated from this solution, or after applying this solution on a substrate, it is dried and subjected to a heat treatment or the like at a temperature of a certain level or more. It is a method to do.

The vapor phase method is a method for obtaining a film-like solid phase by a method such as vapor deposition, sputtering, or CVD. According to the vapor phase method, since Ca, Sr, Ba and Sn have a specific ratio, one or more selected from Ca, Sr and Ba, Sn, O It is also possible to obtain an amorphous compound mainly composed of (oxygen).

This amorphous film is also chemically more stable than CaO, SrO, and BaO and has a higher secondary electron emission efficiency than MgO, so that the driving voltage of the PDP can be reduced. However, the chemical stability is higher for the crystalline compound, and as a synthesis method, the vapor phase method is more expensive than the solid phase method, and thus the crystalline compound is more desirable.

As described above, in consideration of the cost from the industrial viewpoint and the crystallinity of the compound to be generated, the synthesis method by the solid phase method is most desirable.

The raw material species used in the solid phase method is not particularly limited, and for example, oxides, hydroxides, halides, carbonates, nitrates, and the like can be used. As for the mixing method, as in the case of the synthesis of the first electron-emitting material, a ball mill, a medium stirring mill, a planetary ball mill, a vibration mill, a jet mill, a V-type mixer, etc., which are usually used industrially, are wet. Alternatively, it can be dry mixed. The solvent to be used can be appropriately selected as in the case of the synthesis of the first electron emission material.

2nd electron emission material 16b is obtained by baking the mixed powder at 1200 ° C. to 1500 ° C. for 15 minutes to 10 hours.

The firing temperature and firing time are appropriately adjusted according to various conditions such as the particle diameter of the raw material used, classification conditions, and the amount of mixed powder. In order to obtain desired discharge characteristics, the firing atmosphere can be performed in an oxidizing or reducing atmosphere. Depending on the amount of the baked powder, it is preferable to go through a calcination step before the main calcination in order to improve homogeneity.

Furthermore, the second electron emission material 16b obtained in the main firing step may be crushed again using a ball mill, a jet mill, or the like to adjust the particle size distribution and fluidity.

(Application of first electron-emitting material 16a and second electron-emitting material 16b)
On the surface of the formed MgO layer 8, the first electron emission material 16a and the second electron emission material 16b thus produced are planarly formed by a spray method, an electrostatic coating method, a slit coating method, a doctor blade method, or a die coating method. Apply to set. However, the coating method is not limited to these, and coating may be performed by other methods.

Considering the manufacturing cost, it is common to use a screen printing method widely used industrially as a thick film forming technique. The screen printing method is also excellent in that the coating amount can be easily controlled by the solid content ratio of the ink used and the specifications of the screen mesh. In addition, it is possible to batch-apply using the ink containing both powders of the first electron-emitting material 16a and the second electron-emitting material 16b at a predetermined ratio, and it is easier to manufacture in a batch, Each may be applied separately. In this case, it is preferable to apply the first electron emission material 16a after applying the second electron emission material 16b for the following reason.

The second electron-emitting material 16b exhibits the effect of reducing the discharge voltage regardless of the surface area exposed to the discharge space, so that the proportion of the particle surface shielded from the discharge space may be reduced. On the other hand, in the first electron emitting material 16a, the effect of shortening the discharge delay time is reduced when the surface area of the particles exposed to the discharge space is reduced.

Accordingly, the second electron emission material 16b is applied first, and then the first electron emission material 16a is applied to expose the first electron emission material 16a preferentially to the discharge space. It is preferable to obtain both the effect of reducing the discharge voltage by the material 16b and the effect of reducing the discharge delay time by the first electron emitting material 16a.

The application amount of the first electron emission material 16a and the second electron emission material 16b is the amount of change in the linearly transmitted light of the front panel before and after the film formation of the first electron emission material 16a and the second electron emission material 16b (visible light). ) Can be set based on the “coverage” defined from the measured values.

This coverage can be expressed specifically by the following formula.

Coverage (%) = [1− (front panel linear transmission light amount before film formation of first electron emission material 16a and second electron emission material 16b) / (of first electron emission material 16a and second electron emission material 16b) Front panel straight transmitted light after film formation)] × 100
According to the results examined by the present inventors, the coverage when the first electron-emitting material 16 a and the second electron-emitting material 16 b are dispersed on the MgO layer 8 is 1. Although it is preferable to coat with a projected area ratio of 0% or more, it is not limited to this range. This coverage can be adjusted by changing the particle diameters of the first electron-emitting material and the second electron-emitting material and the coating weight thereof. It is preferable to appropriately adjust the coating weights of the two types of materials according to the particle diameter of the materials to be used so as to obtain the best characteristics as a PDP.

Regarding the upper limit of the coverage, if a large amount of the first electron-emitting material 16a and the second electron-emitting material 16b are disposed on the dielectric layer or the MgO layer, the visible light generated by the phosphor is scattered and visible. Since the light transmittance decreases, it is desirable to set the coverage to 50% or less.

The first electron emission material 16 a and the second electron emission material 16 b may be disposed in the entire region on the MgO layer 8, but the first electrons are partially formed in any region on the MgO layer 8. It is also possible to dispose the emission material 16a and the second electron emission material 16b. For example, it may be disposed only on the scan electrode 5 and the sustain electrode 4, or may be disposed only in the central region of each discharge cell.

In the present embodiment, the first electron emission material 16 a and the second electron emission material 16 b are dispersed on the surface of the MgO layer 8, but without forming the MgO layer 8 on the dielectric layer 7. The first electron emission material 16a and the second electron emission material 16b may be directly dispersed.

(Effects of PDP1)
According to the PDP 1 described above, the first electron-emitting material composed of MgO fine particles containing halogen atoms, the second fine particle composed of one or more selected from Ca, Sr, and Ba, and compounds composed mainly of Sn. The electron emission material is present on the surface of the dielectric layer 7 so as to face the discharge space.

Here, since both the first electron-emitting material and the second electron-emitting material have a high secondary electron emission coefficient, the PDP 1 can be driven at a low voltage. In particular, the first electron emission material is also excellent in the effect of suppressing the discharge delay.

Therefore, compared to the PDP 1x according to the above-described prior art, which does not have electron-emitting fine particles on the MgO layer, the PDP 1 according to this embodiment can be driven at a low voltage with a reduced discharge delay.

Further, even if the amount of the first electron emitting material and the second electron emitting material disposed on the MgO layer is small, it is possible to obtain a discharge delay suppressing effect and a driving voltage reducing effect. That is, it is possible to obtain a discharge delay suppressing effect and a driving voltage reducing effect while ensuring the visible light transmittance of the front panel.

In addition, in the PDP 1, the first electron emission material and the second electron emission material are present on the MgO layer, so that the discharge delay reduction effect and the drive voltage reduction effect can be stably obtained for a long time. Although the mechanism is unknown in detail at present, it is an effect obtained by the coexistence and interaction of different materials such as the first electron emission material 16a and the second electron emission material 16b.

The PDP according to the example of the present invention was manufactured together with a comparative example, and a performance evaluation test was performed. Of course, the configuration of the example and the method of the performance evaluation test do not limit the present invention.

Example 1
The first electron-emitting material was manufactured as follows.

Mg (OH) ₂ having a purity of 99.99% was used as the MgO precursor. Further, magnesium fluoride having a purity of 99.9% was used as a sintering aid. 0.25 mol% of magnesium fluoride with respect to Mg (OH) ₂ was weighed and added, and wet-mixed in pure water using a planetary ball mill and zirconia beads. After drying this mixture, it was crushed in a mortar and fired in a high purity alumina crucible. The firing temperature was 1200 ° C., and the firing was continued for 15 minutes.

The fired MgO fine particles were dry pulverized using a ball mill and passed through a nylon mesh to remove coarse particles, which was used as the first electron emission material.

On the other hand, for the second electron emission material, three types of samples were manufactured as follows.

As starting materials, 99.99% pure CaCO ₃ , SrCO ₃ , BaCO ₃ and SnO ₂ were prepared.

Then, for each of CaCO ₃ , SrCO ₃ , and BaCO ₃ , these raw materials are weighed so as to have an equimolar number with SnO _2, and wet-mixed in pure water using a planetary ball mill and zirconia beads, Three types of mixtures (a mixture of CaCO ₃ and SnO _2, a mixture of SrCO ₃ and SnO _{2, and} a mixture of BaCO ₃ and SnO ₂ ) were obtained.

After drying each mixture, it was crushed in a mortar and fired in a high-purity alumina crucible. The firing temperature was 1200 ° C., and the firing was continued for 15 minutes. The fired powder was dry-ground using a ball mill and passed through a nylon mesh to remove coarse particles as a second electron emission material.

The resulting 3 kinds of powder by X-ray diffraction analysis, a single phase of each CaSnO _3, single-phase SrSnO _3, was confirmed to be a single phase of BaSnO _3.

The average particle diameter of the first electron emitting material and the second electron emitting material was 1 μm.

The first electron-emitting material synthesized as described above and each second electron-emitting material were applied on the MgO layer as follows.

The first electron-emitting material and the second electron-emitting material are mixed at a weight ratio of 3: 1 to create a mixed powder, and the mixed powder, a solvent, and a resin are mixed, and a three-roll mill is prepared. And kneaded to obtain an ink for screen printing. On the MgO layer previously formed on the front panel glass, the first electron-emitting material and the second electron-emitting material were collectively applied using a screen printing method so that the coverage was 4.5%. After film formation, the film was dried at 100 ° C. for 1 hour and then baked at 500 ° C. for 3 hours to burn off organic components.

Three types of AC surface discharge type PDPs were prepared using the three types of front panels thus obtained. (The discharge gas is Xe 100% 150 Torr)
(Comparative Example 1)
An AC surface discharge type PDP was produced in the same manner as in Example 1 except that a front panel without the first electron emitting material 16a and the second electron emitting material 16b was used.

(Comparative Example 2)
An AC surface discharge type PDP was produced in the same manner as in Example 1 except that a front panel in which only the first electron-emitting material containing a halogen atom was disposed on the MgO layer was used.

Note that the weight of the first electron-emitting material disposed was the same as the weight of the first electron-emitting material disposed in Example 1.

(Comparative Example 3)
Mg (OH) ₂ to which no magnesium fluoride was added was fired in the same manner as in the production of the MgO fine particles of Example 1 to synthesize MgO fine particles (MgO fine particles containing no halogen atoms). An AC surface discharge type PDP was produced in the same manner as in Example 1 except that a front panel in which only MgO fine particles not containing halogen atoms were disposed on the MgO layer was used.

The weight of the MgO fine particles disposed was the same as the weight of the first electron-emitting material disposed in Example 1.

(Comparative Example 4)
An AC surface discharge type PDP was produced in the same manner as in Example 1 except that a front panel in which only the second electron emission material was disposed on the MgO layer was used.

The weight for disposing the second electron-emitting material was the same as the weight for disposing the second electron-emitting material in Example 1.

(Performance evaluation method)
The initial discharge delay time and the discharge start voltage were evaluated for the PDPs according to Example 1 and Comparative Examples 1 to 4 manufactured as described above. Further, after the initial evaluation, the number of sustain pulses was increased to three times the normal number and the white lighting display was continued for 400 hours, and then the discharge delay time and the discharge start voltage were measured again.

As a specific method for measuring the discharge delay time, a data pulse and a scanning pulse are repeatedly applied to an arbitrary pixel in each PDP, and the light emission of the phosphor accompanying the discharge is received by the optical sensor module. The waveform and the received light signal waveform were measured by observing with a digital oscilloscope.

The time from the application of a pulse to the occurrence of discharge (discharge delay time) was measured 100 times, and the average of the maximum and minimum values of the measured discharge delay time was calculated as the discharge delay time.

On the other hand, the discharge start voltage is determined by connecting the panel to the drive circuit, inputting the drive waveform shown in FIG. 3 to display white lighting, and measuring the minimum value of the sustain voltage at which lighting can be confirmed in all areas. It was.

(Results and discussion of performance evaluation)
For each PDP of Example 1 and Comparative Examples 1 to 4, the discharge delay time after the initial and 400 hr lighting is shown in FIG. 5, and the discharge start voltage after the initial and 400 hr lighting is shown in FIG. Use As for Example 1, CaSnO ₃ as the second electron emitting material, SrSnO _3, there are three types using BaSnO _3, in FIGS. 5 and 6, a typically BaSnO ₃ as the second electron emitting material Shows the results for what was.

Regarding the discharge delay time, compared with Comparative Example 1 corresponding to the conventional general panel configuration, Comparative Example 3 and Comparative Example 4 do not have the effect of reducing the discharge delay time compared to Comparative Example 1. On the other hand, in Comparative Example 2 in which the first electron-emitting material containing halogen atoms is provided, the initial discharge delay time is greatly shortened. Further, in Example 1, although inferior to Comparative Example 2, the discharge delay time is shortened compared to Comparative Example 1, and the discharge delay is reduced to about 30 nsec, so that it can be driven at high speed without causing a lighting failure. I understand.

Note that the discharge delay time shortening effect of Example 1 is inferior to that of Comparative Example 2 because the first electron-emitting material and the second electron-emitting material are mixed in Example 1, and thus the first electron-emitting material. Is partially shielded by the second electron emission material, and it is assumed that the characteristics of the first electron emission material and the second electron emission material are offset.

On the other hand, in Comparative Examples 1 to 4, the discharge delay time after lighting for 400 hr is longer than the initial discharge delay time, and there is a tendency for the characteristics to deteriorate over time. In Example 1 in which the two-electron emission material is mixed and disposed, the discharge delay time after lighting for 400 hr is almost the same as the initial discharge delay time.

In Example 1, it is not clear why the time-dependent change in the discharge delay time is small, but the first electron-emitting material 16a and the second electron-emitting material 16b, which are different from each other, coexist and are specific in the discharge space. It seems that the phenomenon is occurring.

Next, with respect to the initial discharge start voltage, as in the case of the discharge delay time, the initial discharge start voltage is lower in Comparative Example 2 than in Comparative Example 1, but in Comparative Examples 3 and 4 and Examples. In 1, the superiority was not seen as compared with Comparative Example 1.

On the other hand, comparing the initial discharge start voltage and the discharge start voltage after 400 hr lighting, in Comparative Examples 1 to 3, the discharge start voltage after 400 hr lighting is higher than the initial discharge start voltage. In Example 4, conversely, the discharge start voltage after lighting for 400 hr is lower than the initial discharge start voltage.

In contrast, in Example 1, the discharge start voltage after lighting for 400 hr is almost the same as the initial discharge start voltage. Thus, in Example 1, the change with time of the discharge start voltage is small because the tendency of Comparative Example 2 in which the first electron-emitting material is provided and the second electron-emitting material are provided as described above. The tendency of the comparative example 4 is opposite, and it is considered that the effect of showing the opposite tendency is combined.

From the above evaluation results of the discharge delay time and the discharge start voltage, even if the PDP is displayed for a long time by using a mixture of the first electron emission material and the second electron emission material as in Example 1, the discharge can be performed. It can be seen that the initial characteristics are maintained for both the delay time and the discharge start voltage characteristics.

In Example 1, it is considered that the initial discharge delay time and the discharge start voltage can be adjusted by adjusting the ratio of the first electron emission material and the second electron emission material.

As a test result of Example 1, the case where BaSnO ₃ was used as the second electron emission material was described. However, the same measurement was performed when CaSnO ₃ and SrSnO ₃ were used as the second electron emission material. It was confirmed that the effect of. However, the greatest effect was obtained when BaSnO ₃ was used. This _is compared to CaSnO 3, SrSnO _3, it considered the stability of BaSnO ₃ is due to the more excellent.

Further, not only CaSnO ₃ , SrSnO ₃ , and BaSnO ₃ are used alone as the second electron-emitting material, but the same effect can be obtained by using a mixture of two or more of these. In addition, since the solid solutions in which these two or more types are dissolved are similar in chemical structure and have similar characteristics, even if these solid solutions are used as the second electron-emitting material, the same effects can be obtained. .

According to the present invention, a high-definition image display PDP can be driven with a low voltage, and can be used for a television set, a display device for a computer, and the like in transportation, public facilities, and homes. is there.

1 PDP
DESCRIPTION OF SYMBOLS 2 Front panel 3 Front panel glass 4 Sustain electrode 5 Scan electrode 6 Display electrode pair 7 Dielectric layer 8 MgO layer 9 Back panel 10 Back panel glass 11 Data electrode 12 Dielectric layer 13 Partition 14 Phosphor layer 15 Discharge space 16a 1st Electron emission material 16b Second electron emission material 17 Protective layer

Claims (9)

1. A plasma display panel in which a first substrate on which an electrode and a dielectric layer are disposed is disposed opposite to a second substrate through a discharge space, and the periphery of both the first and second substrates is sealed. ,
   On the surface of the dielectric layer, facing the discharge space,
   A first material comprising MgO fine particles containing a halogen atom;
   A plasma display panel in which one or more kinds selected from Ca, Sr, and Ba and a second material made of a fine particle compound containing Sn as a main component are disposed.
2. On the discharge space side of the dielectric layer, a surface layer containing a metal oxide mainly composed of MgO is provided,
   The first material and the second material are:
   The plasma display panel according to claim 1, wherein the plasma display panel is disposed on a discharge space side of the surface layer.
3. The halogen atom is
   The plasma display panel according to claim 1, wherein the plasma display panel is included in the vicinity of a surface layer of the MgO fine particles.
4. The halogen atom is
   The plasma display panel according to claim 1 or 2, which is a fluorine atom or a chlorine atom.
5. The compound constituting the second material is
   3. The plasma display panel according to claim 1, wherein the plasma display panel is a crystalline oxide containing one or more kinds selected from Ca, Sr, and Ba and Sn at a specific ratio.
6. The compound constituting the second material is
   CaSnO _3, SrSnO _3, BaSnO ₃ or a plasma display panel according to claim 1 or 2, of these two or more kinds of solid solutions.
7. A metal oxide layer forming step of forming a metal oxide layer on a surface of the dielectric layer with respect to a first substrate including an electrode and a dielectric layer;
   A method for manufacturing a plasma display panel, comprising: a sealing step in which a first substrate on which the metal oxide layer is formed and a second substrate are disposed opposite to each other and sealed;
   Between the metal oxide layer forming step and the sealing step, on the surface of the metal oxide layer,
   A plasma display panel having a step of disposing a first material composed of MgO fine particles containing a halogen atom and one or more selected from Ca, Sr, Ba, and a fine particle compound second material mainly composed of Sn. Production method.
8. As the first material,
   One or more kinds selected from magnesium fluoride, magnesium chloride, aluminum fluoride, calcium fluoride, lithium fluoride, magnesium chloride, aluminum chloride, calcium chloride, lithium chloride, and sodium chloride are sintered to the MgO precursor. The method for producing a plasma display panel according to claim 7, wherein MgO fine particles obtained by firing a material added as an auxiliary agent are used.
9. In the step of disposing the first material and the second material,
   The method of manufacturing a plasma display panel according to claim 7, wherein the first material is disposed on the surface of the metal oxide layer, and then the second material is disposed.

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