JP2001118518A - Plasma display panel and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To improve display performance of a plasma display panel, that is, to significantly reduce flickering of an image and contribute to improvement of luminous efficiency. SOLUTION: In the PDP of the present invention, the protective film is made of NaCl.
It contains a mixed crystal film oriented in <110> and <100> of a type crystal structure. Further, the crystal columns of the protective film are oriented at an angle of 5 to 60 degrees with respect to the film thickness direction. For the formation of such a protective film, the former is suitable for the CVD method in which the crystallinity is easily controlled, and the latter is suitable for the vacuum evaporation method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a plasma display panel (hereinafter, referred to as PDP) and a method for forming a protective film of the PDP.

[0002] In recent years, PDPs have been positioned as the most prominent for large flat panel displays, and are also suitable for displaying moving images.
It is the centerpiece of displays in the digital technology society. In the future, it is expected that higher image quality and higher efficiency will be promoted.

[0003]

2. Description of the Related Art In a conventional PDP, as shown in FIG. 7, a front plate 101 and a rear plate 106 are opposed to each other. A plurality of pairs of the display electrodes 103 and the display electrodes 105
A 40 μm-thick dielectric layer 104 made of a low-dielectric glass and covering the surface of the dielectric layer 104 with a protective film 10
For example, an MgO film of 8000 ° is formed. As a method of forming the MgO film, generally, a vapor deposition method, a sputtering method, a method of applying a paste containing a liquid organic acid metal salt or a powder of MgO, and the like are used. on the other hand,
On the inner surface of the back plate 106, partition walls 11 for partitioning the discharge space are provided.
0 and the data electrode 108 are arranged in parallel, and a phosphor 111 is applied in a cell separated by each partition 110. Then, the front plate 101 and the rear plate 106
After being overlapped facing each other, the periphery is sealed,
The discharge space is evacuated, and a neon mixed gas containing several volume% of xenon is sealed.

Further, recently, erroneous discharge between individual discharge cells isolated between partition walls, noise reduction due to vibration between the partition walls and the front plate, increase in internal gas pressure, and expansion of the panel under low pressure. It has been proposed to apply a low-melting glass to the upper end of the partition wall and to join the partition wall and the front plate with the low-melting glass for the purpose of preventing the occurrence of cracks (JP-A-5-334).
No. 956, JP-A-9-259754).

[0005] The PDP 114 thus constructed
By applying a voltage to the data electrode 108 and the display electrode 103 at an appropriate timing, a discharge occurs in a space 112 defined by a partition 110 corresponding to a display pixel,
Ultraviolet rays are generated by xenon gas. An image can be displayed by emitting visible light from the phosphor excited by the ultraviolet light.

[0006]

The causes of the deterioration of the display performance of the PDP include the problem of image flickering and low luminous efficiency. As flickering of this image, that is, image quality and luminous efficiency,
The protective film in contact with the discharge space and the discharge gas are important factors.

This protective film is required to increase the secondary electron emission ratio γ to lower the firing voltage, and to increase the sputter resistance in order to extend the life.
In current PDPs, an MgO film is generally used. The orientation of the MgO film depends on the process conditions for forming the film. At present, in order to satisfy the discharge starting voltage and the sputter resistance, the MgO film has to be <111> with respect to the substrate.
It is considered that a film oriented in the <110> direction is preferable.
663909 and JP-A-10-106441). It is also considered that high crystallinity and large crystal grain size are superior. Although this idea is sufficient in terms of lowering the discharge starting voltage, there are many points that have not yet been solved in terms of display performance, that is, image flickering. It is considered that the flickering of the image is caused by a slight fluctuation of the operating point voltage at which the discharge is started or by a discharge delay.

On the other hand, regarding the luminous efficiency, in the PDP,
This is an immediate issue. The principle of light emission of a PDP is basically the same as that of a fluorescent lamp. By generating a glow discharge, ultraviolet rays are generated from Xe to excite the phosphor to emit light. However, since the efficiency of converting the discharge energy into ultraviolet light and the efficiency of converting phosphors into visible light are low, it is difficult to obtain high brightness like fluorescent lamps. Is said to be about 0.2% (Optical Technology Contact V01.3)
4, No. 1, P25, '96).

In recent years, various efforts have been made to improve the luminous efficiency. For example, a mixed gas of three components of argon-neon-xenon is used (Japanese Patent Publication No. 5-5).
Attempts have been made to devise the composition of the discharge gas, such as using a mixed gas of three components of helium-neon-xenon (Japanese Patent No. 2616538). However, their luminous efficiencies are about 1.1 lm / W. At present, sufficient effects have not been obtained.

An object of the present invention is to improve the display performance of these PDPs, that is, to greatly reduce flickering of an image and to contribute to improvement of luminous efficiency.

[0011]

According to a first aspect of the present invention, a discharge gas is sealed in a gas discharge space sandwiched between a pair of opposed substrates, and the discharge gas is filled with the discharge gas. A plasma display panel having a protective film formed in contact therewith, wherein the protective film includes a mixed crystal film oriented in <110> and <100> of a NaCl type crystal structure. Although it has been described that the MgO film is generally used as the protective film, the protective film having the NaCl-type crystal structure is easily affected by the process conditions for forming the film or the underlayer. >, <100> oriented film grows. This orientation is not limited to one direction, but <1
By using a protective film in which crystals oriented in two directions of 10> and <100> coexist, the efficiency could be dramatically improved. Further, when the gas pressure is increased by using this protective film, the effect is further enhanced.

In the conventional PDP, the ultraviolet rays generated by the discharge have most of the resonance lines (central wavelength: 147 nm), whereas the ultraviolet rays generated by the discharge have a high discharge gas pressure (that is, they are sealed in the discharge space). (When the number of atoms present is large), the ratio of molecular beams (center wavelengths 154 nm and 172 nm) increases. Here, while the resonance line has self absorption, the molecular beam has almost no self absorption. As a result, since the amount of ultraviolet light applied to the phosphor layer does not decrease, the luminance is improved as compared with the case where the gas pressure is low, and as a result, the luminous efficiency is improved.

When the gas pressure is increased, the present inventors have found that the MgO film of the protective film in contact with the discharge gas is not a unidirectionally oriented film but a mixed crystal film of <110> and <100>. Found it to be efficient. Although the reason for this is not clear, it is probably because the proportion of molecular beams has increased, or the discharge mode has changed, and an ineffective current has stopped flowing. However, the fact is not clear.
Further, by appropriately selecting the xenon ratio in the discharge gas, the discharge starting voltage and the efficiency can be further improved. The gas pressure was effective in the range of 300 to 4000 Torr. Here, the protective film oriented in two directions is <110>
It is preferred that they are preferentially oriented. Further, the mixture ratio of <110> and <100> crystals in the protective film [<110> /
<100>] is preferably 3 or more and 5 or less.

[0014] In a second aspect of the present invention, the opposing 1
A plasma display panel in which a discharge gas is sealed in a gas discharge space sandwiched between a pair of substrates, and a protective film is formed so as to be in contact with the discharge gas, wherein the protective film is made of Na
It has a Cl-type crystal structure, and the crystal column of the protective film is oriented at an angle of 5 to 60 degrees with respect to the film thickness direction. It is generally known that a film having a NaCl type crystal structure such as MgO has a crystal column which grows in a film thickness direction and is vertically aligned as shown in FIG.
By giving the crystal column a certain angle with respect to the film thickness direction, the secondary electron emission ratio γ value of the protective film can be further increased, and the discharge delay can be significantly improved. As a result, not only can the discharge starting voltage be lowered, but also the flicker of the image can be improved. Here, the protective film is <110>, <111>, <100>, <211>
It is preferred that they are preferentially oriented. Also, <110>
And a mixed crystal film preferentially oriented to <100>. Further, the gas pressure is preferably in the range of 300 to 4000 Torr.

According to a third aspect of the present invention, there is provided a method (hereinafter, referred to as a CVD method) in which the protective film formed in the first aspect is formed by decomposing a compound vapor and a reaction gas in a reduced-pressure plasma to cause a reaction. A PDP manufacturing method. In the vacuum evaporation method and the sputtering method, it is possible to control by changing the film forming temperature and the film forming rate of the sample. However, in consideration of the problem of heat history before and after the process, the film forming temperature is set to about 400 ° C. It is almost difficult to produce a mixed crystal film as it is. On the other hand, C
In the VD method, a film in which bidirectional crystalline films of <110> and <100> are mixed can be produced without changing the film forming temperature by changing the gas flow rate or the like.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a PDP, wherein the protective film according to the second aspect is formed by using a vacuum deposition method. Although it is difficult to control to mix crystal films in two directions, the crystal column has a certain inclination with respect to the film thickness direction by making simple contrivances such as making the deposition molecules enter the substrate obliquely. Can be made.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a plasma display panel and a method of forming a protective film according to the present invention will be described with reference to the drawings.

(First Embodiment of the Invention) FIG. 1 is a diagram showing a main part of a PDP according to the present invention. FIG. 2 is a schematic diagram of a protective film forming apparatus according to the present invention. FIG. 3 is a schematic diagram of a cross section of a protective film of the PDP according to the first embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of a protective film formed by a conventional method according to Comparative Example 1.

As shown in FIG. 1, the PDP of the present invention has
A silver paste (for example, NP-4028 manufactured by Noritake) on a front glass 102 having a thickness of 00 mm, a width of 300 mm, and a thickness of 3 mm.
Is printed and baked in a line having a thickness of 5 μm and a width of 80 μm,
The display electrode 103 is formed. Next, the display electrode 103
75% by weight of Pb containing an organic binder (α-terpinel containing 10% of ethylcellulose) to cover Pb
A lead-based dielectric layer paste composed of O, 15% by weight of B ₂ O ₃ , and 10% by weight of SiO ₂ is printed and baked by a screen printing method to obtain a dielectric layer having a thickness of 40 μm. A film is formed on this dielectric layer by a CVD method while adjusting the flow rate of oxygen so that the crystal grain size becomes 40 to 50 nm.

This CVD method will be described in detail. Ma
First, the front glass 102 is set in an apparatus as shown in FIG.
Then, the substrate is heated to 350 ° C. by the substrate heating lamp 117. Mind
Magnesium acetylacetonate (Mg (C
_FiveH₇O_Two)_Two) And heated to 220 ° C. Soshi
Source gas supply valve and carrier gas supply valve
Is opened, and 50 sccm of nitrogen is supplied from the raw material gas supply port 119.
The gas is Mg (acac) _TwoWith the raw material gas that became steam
Is introduced into the film forming chamber 116. At the same time, turn on the oxygen supply valve
Open the oxygen gas as a reaction gas from the oxygen gas supply port 120
(Flow rate 500 sccm) is similarly introduced into the film forming chamber 116.
You. Next, a frequency of 13.56 MHz from the high frequency power supply 121 is applied.
A frequency electric field of 1.2 kW is applied, and plasma is applied on the electrode 122.
Generates 123 and has a film thickness of 3000 ° as shown in FIG.
Mixed crystal with an in-plane ratio of <110> and <100> of 4: 1
The obtained MgO film is obtained. Here, the in-plane ratio is JCPDS
And the fitting curve obtained from the XRD results.
It is the ratio of the value obtained by multiplying the product with the area of the probe. During film formation
The pressure is 0.08 Torr. In this way, before
The face glass is completed.

On the other hand, a silver paste (for example, NP-4028 manufactured by Noritake) is coated on the front glass 102 with a thickness of 5 μm.
Printed and baked in a line shape with a width of 80 μm, the data electrode 10
Get 8. Next, a glass paste (for example, Noritake N
P-7973) is printed and fired at a film thickness of 20 μm to obtain a dielectric layer 109. Further, multi-layer printing is performed on the dielectric layer 109 with a screen plate so as to be parallel to the data electrodes 108, and baking is performed to obtain partition walls 110. The fluorescent material 111 is placed in the discharge space formed by the partition 110.
Is printed and fired to complete the back plate.

The front plate 101 and the back plate 106 are overlapped so as to face each other, the inside is evacuated to a vacuum, and a mixed gas of 95% by volume of neon and 5% by volume of xenon is supplied at 500 Torr.
To complete the PDP 114.

The cell size of this PDP is 0.3 × 0.
9 mm.

Comparative Example 1 A PDP similar to that of the first embodiment of the present invention was manufactured. However, the same C is used for the protective film.
An MgO film of <110> orientation was formed by the VD method (FIG. 5).
The film thickness is 3000 ° which is the same as in the first embodiment.

Comparative Example 2 A PDP similar to that of the first embodiment of the present invention was manufactured. However, the same C is used for the protective film.
A <100> oriented MgO film was formed by the VD method. The film thickness is 3000 ° which is the same as in the first embodiment.

Comparative Example 3 A PDP similar to that of the first embodiment of the present invention was manufactured. However, as for the protective film, an MgO film (<111> orientation) by a conventional method of electron beam evaporation.
Was formed. The film thickness is 3000 ° which is the same as in the first embodiment.

The P produced in this example and Comparative Examples 1, 2, and 3
When the DP was displayed by the same operation circuit, the results shown in (Table 1) were obtained. From this result, the PDP of the present invention is the same as the conventional PDP
It can be seen that the display performance is superior to that of DP.

[0028]

[Table 1]

In the first embodiment of the present invention, MgO
Although the mixed crystal ratio of <110> and <100> was set to 4 in the film, the film formation conditions were changed. As a result, it was found that the efficiency was significantly improved when the film was set to 3 or more and 5 or less. Therefore, the mixing ratio is preferably 3 or more and 5 or less.

Further, in the first embodiment, the thickness of the MgO film is 3000 °, but what is required is the surface condition of the protective film in contact with the discharge space, and therefore the thickness is not limited to this.

In the first embodiment, the CVD method is used as a method for forming the protective film. However, depending on the manufacturing conditions, a conventional vapor deposition method, sputtering method, or other film forming methods can be used. is there. However, the CVD method is preferable to satisfy the constraints such as the film thickness and the sample temperature.

(Embodiment 2) PDP of the present invention
Is 200 mm long and 300 m wide, as in the first embodiment.
m On a front glass 102 having a thickness of 3 mm, a silver paste (for example, NP-4028 manufactured by Noritake) is coated with a film having a thickness of 5 μm and a width of 8 μm.
The display electrode 103 is formed by printing and firing in a 0 μm line shape. Next, 75% by weight of PbO containing an organic binder (α-terpinel containing 10% of ethylcellulose) and 15% by weight of B ₂ so as to cover the display electrode 103
O ₃ , a lead-based dielectric layer paste composed of 10% by weight of SiO ₂ is printed and baked by a screen printing method to have a film thickness of 40%.
A μm dielectric layer 104 is obtained. On the dielectric layer 104, an MgO film in which a crystal column having a <111> direction has an angle of 30 degrees with respect to the film thickness direction is formed by an electron beam vacuum evaporation method, and a protective film 105 is obtained (FIG. 6). In this vacuum deposition method, an incident angle of 30 degrees was given to the substrate on which the evaporated matter of MgO was formed. Thus, the front plate 101 is completed.

On the other hand, the back plate 106 is manufactured in the same manner as in the first embodiment. The front plate 101 and the back plate 106 are overlapped so as to face each other. At this time, in order to set the gas pressure filled as the discharge gas to be higher than the atmospheric pressure, the partition wall 110 of the back plate and the protective film 105 of the front plate are bonded to a low-melting glass joining member 115 (for example, Asahi Glass ASF-2).
000) (FIG. 4). This joining member 115
It is formed on the partition 110 using printing. Finally, the discharge space is evacuated, and a mixed gas of 95% by volume of neon and 5% by volume of xenon is sealed up to 1500 Torr.
The PDP 114 is completed. The cell size of this PDP is 0.3 × 0.9 mm.

Comparative Example 4 A panel similar to that of Embodiment 2 of the present invention was manufactured. However, for the protective film, MgO of <111> vertical orientation by electron beam evaporation, which is a conventional method, is used.
A film was formed. The film thickness is 3000 ° as in the second embodiment.

Comparative Example 5 A panel similar to that of the second embodiment of the present invention was manufactured. However, for the protective film, MgO of <110> vertical orientation by electron beam evaporation, which is a conventional method, is used.
A film was formed. The film thickness is 3000 ° as in the second embodiment.

When the PDPs manufactured in this embodiment and Comparative Examples 3 and 4 were displayed by the same operation circuit,
The results are shown in (Table 2). From these results, the PD of the present invention
It can be seen that P shows superior display performance as compared with the conventional PDP.

[0037]

[Table 2]

In the second embodiment, the thickness of the MgO film is 3000 °, but what is required is the crystalline state of the surface of the protective film in contact with the discharge space, and therefore the thickness is not limited to this.

In the second embodiment, the discharge gas pressure is set to 1500 Torr. However, when the discharge gas pressure exceeds 300 Torr, the amount of generated ultraviolet rays increases, and as a result, an improvement in efficiency can be expected. Further, if the gas pressure is increased, further effects can be expected.However, since the discharge starting voltage becomes a voltage higher than practical use and it becomes difficult to produce a panel, preferably,
600 to 4000 Torr.

In the second embodiment, the angle of the crystal column of the protective film is set to 30 degrees with respect to the film thickness direction. As a result of studying by changing the angle, when the angle exceeds 60 degrees, image flickering often occurs. Not only that, the film formation rate is extremely reduced, and the uniformity of the film thickness within the panel is also a problem. Therefore, the preferable angle is 5 to 60 degrees.

In this embodiment, a vacuum deposition method is used as a method for forming a protective film. However, if an ion plating method is used, the film structure and orientation can be further controlled. In addition, if the film formation method is devised, a film can be formed by tilting the crystal column by a CVD method, a sputtering method, or the like.

In the present embodiment, the MgO film is used as the protective film. However, if the protective film has a high secondary electron emission ratio and the film shows crystallinity and the crystal grain size can be controlled, the film can be controlled. Needless to say, the same effect can be obtained. Other Na
As the Cl-type crystal structure, for example, MgF ₂ , Ca
_{O, SrO, BaO, Y 2} O 3, and the like lanthanides.

[0043]

As described above, according to the present invention, the opposing 1
A plasma display panel in which a discharge gas is sealed in a gas discharge space sandwiched between a pair of substrates, and a protective film is formed so as to be in contact with the discharge gas, wherein the protective film is N
By forming a mixed crystal film oriented in <110> and <100> of the aCl type crystal structure, discharge efficiency can be drastically increased.

Further, in the present invention, in order to form the protective film as a mixed crystal film oriented in <110> and <100> of the NaCl type crystal structure, the vapor of the compound and the reaction gas are decomposed in a reduced-pressure plasma to react. By using a method for performing the method, that is, the CVD method, the ratio of the <110> and <100> mixed crystal films can be controlled to a predetermined ratio, and a PDP with high discharge efficiency can be provided.

Further, according to the present invention, in the plasma display panel in which a discharge gas is sealed in a gas discharge space sandwiched between a pair of opposing substrates and a protective film is formed so as to be in contact with the discharge gas, Has a NaCl-type crystal structure, and the crystal column of the protective film is oriented at an angle of 5 to 60 degrees with respect to the film thickness direction. The delay can be significantly improved. Furthermore, when producing a protective film in which the crystal column has a certain angle,
By using the vacuum evaporation method by oblique incidence of the evaporating substance, a PDP with high discharge efficiency and less flickering of an image can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a PDP according to the present invention.

FIG. 2 is a schematic diagram of a protective film forming apparatus according to the present invention.

FIG. 3 is a schematic cross-sectional view of a protective film of the PDP according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a main part of a PDP according to a second embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of a protective film of a PDP formed by a conventional method according to Comparative Example 1.

FIG. 6 is a schematic view of a cross section of a protective film of a PDP according to a second embodiment of the present invention.

FIG. 7 is a schematic diagram showing a conventional PDP.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Front plate 102 Front glass 103 Display electrode 104 Dielectric layer 105 Protective film 106 Back plate 107 Back glass 108 Data electrode 109 Back plate dielectric 110 Partition 111 Fluorescent substance 112 Space part 114 PDP panel 115 Joining member 116 Film forming chamber 117 Substrate Heating lamp 118 Vaporizer 119 Source gas supply port 120 Oxygen gas supply port 121 High frequency power supply 122 Electrode 123 Plasma

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01J 11/00 H01J 11/00 K (72) Inventor Akira Shiokawa 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial F term in reference (reference)

Claims (16)

[Claims] 1. A plasma display panel in which a discharge gas is sealed in a gas discharge space sandwiched between a pair of opposing substrates, and a protective film is formed so as to be in contact with the discharge gas. <110> having a NaCl type crystal structure
And a mixed crystal film oriented in <100>. 2. The plasma display panel according to claim 1, wherein the protective film is preferentially oriented to <110>. 3. The <110> crystal and the <100> crystal in the protective film.
2. The plasma display panel according to claim 1, wherein a mixture ratio of crystals [<110> / <100>] is 3 or more and 5 or less. 4. A plasma display panel in which a discharge gas is sealed in a gas discharge space sandwiched between a pair of substrates facing each other, and a protective film is formed so as to be in contact with the discharge gas. A plasma display panel having a crystal structure of a type, wherein a crystal column of the protective film is oriented at an angle of 5 to 60 degrees with respect to a film thickness direction. 5. The plasma display panel according to claim 4, wherein the protective film is preferentially oriented to <110>. 6. The plasma display panel according to claim 4, wherein the protective film is preferentially oriented to <111>. 7. The plasma display panel according to claim 4, wherein the protective film is preferentially oriented to <100>. 8. The plasma display panel according to claim 4, wherein the protective film is preferentially oriented to <211>. 9. The plasma display panel according to claim 4, wherein the protective film includes a mixed crystal film preferentially oriented to <110> and <100>. 10. The plasma display panel according to claim 1, wherein the protective film is an MgO film. 11. The gas pressure of the enclosed discharge gas is:
The plasma display panel according to any one of claims 1 to 10, wherein the pressure is 300 to 4000 Torr. 12. The plasma display panel according to claim 1, wherein the sealed discharge gas contains at least xenon. 13. The plasma display panel according to claim 1, wherein the protective film is formed by decomposing and reacting a compound vapor and a reaction gas in a reduced-pressure plasma. Production method. 14. The method according to claim 4, wherein the protection film is formed by a vacuum deposition method. 15. The method according to claim 14, wherein the vacuum deposition method is a method in which a deposition material is obliquely incident on the substrate. 16. The method according to claim 14, wherein the vacuum deposition method is an ion plating method.