JP2002038146A - Phosphor and phosphor ink for inkjet method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a fluorescent substance layer of a highly precise plasma display panel with a high accuracy at a low cost. SOLUTION: This unconventional high-accuracy and inexpensive plasma display panel is obtained by using a fluorescent substance powder coated with an oxide or a fluoride having a positive electrostatic charge in the fluorescent substance layer of the plasma display panel and continuously carrying out rendering or filling with a low-viscosity ink good in fluidity and prepared by decomposing an ink with a jet mill.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma display panel used for a display device or the like, and more particularly to a method for forming a phosphor layer of a plasma display panel.

[0002]

2. Description of the Related Art FIG. 3 is a schematic sectional view of an alternating current (AC) type plasma display panel. In FIG. 3, 3
Reference numeral 1 denotes a front cover plate (front glass substrate) on which a display electrode 32 is provided, on which a dielectric glass layer 33 and a magnesium oxide (MgO) dielectric having a crystal orientation of MgO oriented to the (111) plane. The body protection layer 34 covers.

Conventionally, the MgO dielectric protective layer 34 has been formed by a vacuum deposition method using electron beam heating mainly using MgO as a raw material (for example, Japanese Patent Application Laid-Open No. Hei 5-342991).
No.).

Reference numeral 35 denotes a back glass substrate (back plate) on which address electrodes 36 and partition walls 3 are provided.
7. A phosphor layer 38 is provided, and 39 is a discharge space in which a discharge gas is sealed. Conventionally, this electrode layer (display electrode and address electrode) is mainly formed by a screen printing method, and the phosphor layer is formed by a conventional screen printing method (for example, JP-A-6-5205). , An ink jet method (for example, JP-A-53-79371), a photoresist film method (for example, JP-A-6-79371).
273925) has been used.

The brightness of a panel conventionally developed as a plasma display panel is a 40-inch NTS.
C panel (640 x 480 cells, cell pitch 0.43 mm x 1.29 mm, cell area about 0.55 m
m ² ) was about 250 cd / m ² .

[0006]

In recent years, expectations for high-definition, large-screen televisions including high-definition televisions have been increasing. CRTs are superior to plasma displays and liquid crystals in terms of resolution and image quality, but they are 4th in terms of depth and weight.
Not suitable for large screens larger than 0 inches.

[0007] The liquid crystal has excellent performance of low power consumption and low driving voltage, but can realize a large screen, and a 40-inch class product has already been developed (for example, Materials Feb. 1996, Vol.
No. 2, 7).

[0008] The brightness of these developed products depends on the intensity of ultraviolet rays emitted by the discharge of gas (He-Xe-based gas or neon-Xe-based gas) sealed in the discharge space. In particular, in the discharge by the He-Xe-based gas, vacuum ultraviolet rays having a wavelength of 147 nm (nanometer) due to the resonance line of Xe are emitted, and the red, green, and blue ultraviolet rays applied in the discharge cell mainly by the ultraviolet rays of this wavelength. The excited phosphor was excited to emit light (for example, Applied Physics Vol. 51, No. 3, 1982, page 33).
4-347. Optical Technology Contact Vol. 34, no.
1 1996, page 25, “Flat display panel '96 5-3” (FLAT PANEL DIS
PLAY 96 'Part 5-3), NHK Technical Research Vol. 31, No. 1, 1979, page 18).

However, the current 40 to 42 inch class plasma display has a pixel level of 64 pixels.
0 × 480 cells, cell pitch 0.43mm × 1.29m
m, the area of one cell is 0.55 mm ² (for example, Functional Materials, February 1996, Vol 1.16, No. 2, page 7).

The width of the display electrode or address electrode is
130 μm to 150 μm. The pixel level of the full-spec high-definition television expected in recent years is 1920 × 1125, the cell pitch is also 42 inch class, 0.15 mm × 0.48 mm, and the area of one cell is 0.072 mm ² . become. Also, the electrode width is reduced to 70 μm. When creating a high-definition television with the same 42-inch size, NT at one pixel cell pitch
Compared to SC, it is 1/3 finer.

For a display monitor, the pixel level of a 20-inch SXGA having a higher definition is 1280 × 1024 pixels, and the cell pitch is 20 inches, which is 0.106 mm × 0.298 mm.
The electrode width is also reduced to about 50 μm. Therefore, it is difficult to perform the electrodes by screen printing.

On the other hand, there also arises a problem that the discharge starting voltage increases due to the decrease in the electrode width.

On the other hand, in the screen printing method, even when the phosphor is applied, when the pitch is 0.1 to 0.15 mm, the partition wall has a width, so that the space in which the phosphor enters is 0.1 to 0.1 mm.
The thickness is about 08 mm, which makes it difficult to accurately and rapidly flow high-viscosity (tens of thousands of centipoise) phosphor ink by a printing method. Also, a phosphor photo film method using a phosphor and an ultraviolet photosensitive resin,
In the phosphor photopaste method, it is possible to fill the inside of the partition wall (the inside of the rib) with a certain degree of accuracy, but there is a problem that the exposure phenomenon must be repeated in three colors, which takes a lot of man-hours.

In the ink-jet method in which a liquid containing a phosphor and an organic binder is ejected from a pressurized nozzle into a charged electrode space and a desired pattern is adhered to the inside of the partition, the conventional phosphor has a surface state of ethyl cellulose. Organic binders such as acrylic resin or polyvinyl alcohol are difficult to adsorb on the surface of the phosphor, or these resins do not dissolve sufficiently in solvents such as terpineol or butyl carbitol acetate. And the nozzles are easily clogged, and it is difficult to apply the phosphor continuously for a long time.

Further, in the ink of the conventional composition, the phosphor and the resin are not very well dispersed, and the surface tension of the ink makes it difficult for the phosphor to adhere to the side wall of the partition wall. There was also a problem.

[0016]

In order to solve the above-mentioned problems, the present invention provides a method of applying a phosphor using a phosphor ink using a conventional ethylcellulose-based, acrylic resin-based or polyvinyl alcohol-based binder. Rather than 5μ coated with a positively charged oxide or fluoride
m or less of a phosphor powder and a solvent such as terpineol or butyl carbitol acetate, which contains at least 49% of an ethoxy group (—OC ₂ H ₅ ) in the cellulose molecule in ethyl cellulose or an ethylene oxide polymer. Method of continuously ejecting phosphor ink from thin nozzles using a binder composed of a binder and a phosphor ink having a high fluidity of 200 centipoise or less, which has enhanced resin adsorption to the phosphor and dispersibility of the ink. By using the phosphor, the phosphor can be sufficiently adhered to the side wall of the partition without being clogged or mixed with the partition at a narrow interval of 150 μm or less by one drawing, and can be formed continuously for a long time. .

In addition, positively charged oxides or fluorides have a low electronegativity and therefore tend to emit electrons (the work function is small), so that it is possible to lower the discharge voltage (for example, “ Solid State Science and Technology ”(J. Electrochem. Soc.
SOLID-STATE SCIENCE AND TECHNOLOGY), Electronic Display Co., Ltd. Ohmsha, July 7, 1995, pp. 82-8
8).

[0018]

Embodiment 1 Hereinafter, a plasma display panel according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view schematically showing an AC surface discharge type plasma display panel according to an embodiment of the present invention. Although only one cell is shown in FIG. 1,
Many cells that emit red, green, and blue light are arranged and PD
P is configured.

This PDP has a display electrode 12 and a dielectric glass layer 13 on a front glass substrate (front cover plate) 11, a front panel of a protective layer 14, an address electrode 16 on a rear glass substrate (back plate) 15, and visible electrodes. A back panel on which the light reflection layer 17, the partition wall 18 and the phosphor layer 19 are arranged is laminated, and a discharge gas is sealed in a discharge space formed between the front panel and the back panel. Fabricated as shown.

(Fabrication of Front Panel) In the front panel, a display electrode 12 is formed on a front glass substrate 11, and the display electrode 12 is covered with a lead-based or bismuth-based dielectric glass layer 13. It is produced by forming a protective layer 14 on the surface.

In this embodiment, the display electrode 12 is a silver electrode, and is formed by a method of screen-printing a paste for a silver electrode and then firing the paste. Further, the composition of the dielectric glass layer 13 of the lead-based, lead oxide [PbO] 70 _{wt%, [2 O 3 B]} 15 % by weight boron oxide, a silicon oxide [SiO _2] 15% by weight, screen printing About 20
It was formed to a thickness of μm. Next, the above dielectric glass layer 13
A protective layer 14 of 1.0 μm magnesium oxide (MgO) was formed thereon by a CVD method (chemical vapor deposition method).

(Preparation of Back Panel) Back glass substrate 15
An address electrode 16 is formed thereon by screen printing a paste for a silver electrode and then firing, and a visible light reflecting layer 17 made of TiO ₂ particles and dielectric glass is formed thereon by screen printing and firing. The glass partition walls 18 obtained by repeating the screen printing and firing are formed at a predetermined pitch.

Then, in each space between the partition walls 18,
The phosphor layer 19 is formed by disposing one of a red phosphor, a green phosphor, and a blue phosphor. The method for forming the phosphor layer 19 and the phosphor material to be used will be described later in detail, but the phosphor ink is applied by a method of scanning while continuously ejecting the phosphor ink from the nozzle, and after the application, about 500 ° C. And fired in air.

In the present embodiment, the height of the partition wall is 0.1 in accordance with a 40-inch class high-definition television.
0.15 mm and the partition wall pitch was 0.15 to 0.3 mm. The phosphor layer 19 formed on the back cover surface and the side wall of the partition is made of phosphor particles having an average particle diameter of 0.5 to 5 μm coated with a positively charged oxide or fluoride.
The thickness was 5 to 50 μm.

(Preparation of PDP by Panel Lamination)
Next, the front panel and the rear panel thus manufactured are bonded to each other using sealing glass so that the front panel, the display electrode, and the address electrode are orthogonal to each other, fired at about 450 ° C., and separated by the partition wall 18. High vacuum (8 ×
The PDP is manufactured by evacuating to 10 ⁻⁷ Torr and filling a discharge gas having a predetermined composition at a predetermined pressure.

In the present embodiment, neon (Ne) is used.
The content of Xe in the xenon (Xe) discharge gas is 1
0% by volume, and the sealing pressure was set in the range of 500 to 800 Torr.

FIG. 2 is a schematic structural view of an ink coating apparatus 20 used for forming the phosphor layer 19. As shown in FIG. 2, in the ink application device 20, a phosphor ink is stored in a server 21, and a pressurizing pump 22 pressurizes the ink and supplies the pressurized ink to a header 23. The header 23 has an ink chamber 23
a and a nozzle 24 are provided, and the ink that has been pressurized and supplied to the ink chamber 23 a is continuously ejected from the nozzle 24.

(Oxide and fluoride are attached to the surface of the phosphor,
Coating method) The method of coating the surface of the phosphor with an oxide or fluoride is as follows: first, red (YGd) BO
₃ : Eu, blue BaMgAl ₁₀ O ₁₇ : Eu, green Zn ₂ Si
After mixing and stirring the suspension of the O ₄ : Mn phosphor and the suspension of the necessary oxide or fluoride coating particles (the particle size is 1/10 or less of the phosphor), the mixture is suction-filtered, and then filtered. After drying at a temperature of at least ℃, baking at 350 ℃. A small amount of resin, organic silane, water glass or the like may be added to improve the adhesion between the phosphor and the oxide or fluoride.

There is also a method of utilizing the hydrolysis of an organometallic compound for coating in a film form. For example, A
When forming a l ₂ O ₃ film, a phosphor with Al (OC ₂ H _{5) 3} is an alkoxide of aluminum, which was mixed and stirred in alcoholic solution, Al ₂ O ₃ on the surface of the phosphor
Coating.

Next, a method of preparing a phosphor ink coated with a positively charged oxide or fluoride will be described.

(Preparation Method of Phosphor Ink) The phosphor ink is prepared by dissolving 0.2% to 10% of each color phosphor, ethylcellulose or polyethylene oxide to which a positively charged oxide or fluoride is first adhered or coated. Solvent such as terpineol, butyl carbitol acetate or pentanediol was jet-milled.
It was mixed and dispersed in a pressure range of ^{Kgf / cm 2 ~100Kgf / cm 2} , to create a phosphor ink to prepare a viscosity of the ink to 10Cp～1000cp.

Using the inks prepared more specifically,
A method of applying a phosphor and forming a panel will be described below.

A screen partition 17 made of glass and having a height of 0.15 mm (interval between partition walls 0.15 mm) is obtained by firing after repeated screen printing.

Next, the particle size of 0.2 μm is stored in the server 21.
Particles with 0.3% MgO particles attached to the phosphor
BaMgAl which is a 3.0 μm diameter blue phosphor_TenO₁₇:
Eu ²⁺50% by weight powder, 49% ethoxy group content
Ethyl cellulose (molecular weight 70,000) 0.3% by weight, solvent (
-Mixed solution of pineole and butyl carbitol acetate
30 kgf using a jet mill.
/ Cm^TwoAt a pressure of 30 centipoise (30 centipoise).
cp).

Next, this coating liquid is poured, and the blue phosphor liquid is jetted into the stripe-shaped partition walls from the nozzle portion 23 (with a nozzle diameter of 100 μm) of the jetting device under the pressure of the pump 22, and at the same time, the substrate is moved linearly. Then, the phosphor ink is filled to the vicinity of the top of the partition wall, and after drying, a blue phosphor line is formed.

Similarly, red (Y _X Gd _{1 -X} ) BO ₃ :
After forming a line of Eu ³⁺ , green Zn ₂ SiO ₄ : Mn, it is baked at 500 ° C. for 10 minutes to form a phosphor layer 18.

Next, the rear glass substrate 15 on which the phosphor layer 18 is provided is bonded to the front panel using sealing glass, and the discharge space 19 is filled with 8 × 10 before filling the discharge gas.
Evacuation was performed to a vacuum of ^-7 Torr, and helium (He) gas containing 10% xenon (Xe) gas was filled as a discharge gas in the discharge space at 500 Torr to obtain an AC surface discharge type plasma display.

Next, when this panel was discharged at a discharge sustaining voltage of 150 V and a frequency of 30 KHz, the wavelength of ultraviolet rays was mainly (from indirect experiments) excited by molecular beams of Xe resonance lines centered at 147 nm and 173 nm. Wavelength, and the panel luminance was 530 cd / m ² . Further, it was confirmed from the measurement of each color of the panel that there was no color mixture. The results are shown in Sample No. 1 in (Table 1).

[0040]

[Table 1]

In the same manner, the type of oxide or fluoride that is positively charged, the particle diameter of the phosphor, the viscosity of the ink (coating liquid) when the type and amount of the resin are changed, and the phosphor on the side wall of the partition wall Samples 1 to 19 in (Table 1) to (Table 5) show data such as how to adhere, the continuous application possible time, and the panel brightness.

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

[0045]

[Table 5]

The viscosity of the mixture (ink) is 1000 centipoise (cp) or less, and preferably 15 to 200 cp, for ejecting the phosphor mixture from the thin nozzle.

In order to suppress the nonuniformity of the coating film due to the clogging of the nozzle and the precipitation of the phosphor with this viscosity, the surface of the phosphor particles is coated with a positively charged oxide or fluoride and the particle size. Is required to be in the range of 0.5 μm to 5.0 μm.

If the amount of the positively charged oxide or fluoride coating on the surface of the phosphor particles is too small, the effect is small. If the amount is too large, vacuum ultraviolet light generated in the plasma is absorbed, and the panel is damaged. Is preferable since the luminance of the phosphor decreases, and the preferable range is 0.05% based on the weight of the phosphor.
~ 2.0%.

[0049]

[Examples] [Examples 1 to 17 and Comparative Examples 18 to 19]
PDPs of materials No. 1 to 17 shown in (Table 1) to (Table 5)
Is based on the above embodiment, the phosphor ink is coated with an oxide or fluoride positively charged with a phosphor powder of 5 μm or less, and ethoxylates in cellulose molecules sufficiently dissolved in terpineol or butyl carbitol acetate as a solvent. A sample in which a binder composed of a polymer of ethyl cellulose or ethylene oxide having a group (—OC ₂ H ₅ ) content of 49% or more and a phosphor ink and the dispersibility of which was increased using a jet mill was used. The discharge gas was Ne-Xe (10
% By volume) of a mixed gas. The height of the partition is 0.1
The space between the 5 mm partition walls was 0.15 mm.

The PDPs of Sample Nos. 18 to 19 are comparative examples, and Sample No. 18 is a negatively charged oxide (S
It shows the state of application of the phosphor and the state of the panel when the phosphor is coated with (IO ₂ ). Material No. 19 shows the state of application of the phosphor and the state of the panel when nothing is coated on the phosphor. Is shown, and other than that, the sample No.
The settings are the same as those of the PDPs 1 to 17.

Consideration: The phosphor inks and panels of Samples Nos. 1 to 17 can be continuously applied for 100 hours or more and have higher brightness than the conventional examples (Nos. 19 to 20). This is presumably because the coating of a positively charged oxide or fluoride improved the dispersion of the phosphor ink, and the phosphor adhered sufficiently to the side surfaces of the partition walls. Although not shown in the table, the discharge starting voltage of the panel was lower than that of the sample No.
Nos. 1 to 17 are 20 bottles lower than the comparative examples (Nos. 19 and 20) and contribute to the reduction of panel power (however,
Panel luminance measurement was 150V for constant comparison of all panels.
It is measured at a constant 30 KHz).

[0052]

As described above, according to the present invention, an excellent method for applying a phosphor with high accuracy, stability, and low cost even when the space between the partition walls is fine is achieved. This is the best method for display panels.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a plasma display panel according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of an ink jet apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic sectional view of a conventional AC type plasma display panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Front glass substrate (front cover plate) 12 Silver electrode (display electrode) 13 Dielectric glass layer 14 Dielectric protection layer 15 Back glass substrate (back plate) 16 Address electrode (silver electrode) 17 Partition wall 18 Phosphor 19 Discharge space 21 Server 22 Pressurizer 23 Injection nozzle 24 Glass substrate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01J 11/02 H01J 11/02 B (72) Inventor Shigeo Suzuki 1006 Kazuma Kazuma, Kadoma City, Osaka Matsushita Electric Industrial Inside (72) Inventor Mitsuhiro Otani 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Hiroyuki Kado 1006, Oaza Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 2H086 BA11 BA45 BA54 BA55 BA59 BA61 4H001 CA01 CC03 CC04 CC05 CC06 CC08 4J039 AB02 BA10 BA13 BA30 BA31 BA32 BA34 BA38 BA39 BC07 BC20 CA01 EA28 FA04 GA24 5C028 FF06 FF11 FF12 FF16 5C040 FA01 GG08 MA02 MA04 MA04

Claims (9)

[Claims] 1. A phosphor for an ink-jet method comprising a phosphor powder to which an oxide or fluoride having a positive charge is attached or coated. 2. An oxide having a positive charge is magnesium oxide (MgO), zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ ), europium oxide (Eu ₂ O ₃ ), neodymium oxide (Nd ₂ O). ₃ ) Dysprosium oxide (Dy ₂
O ₃ ), lead oxide (PbO), indium oxide (In)
₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), magnesium aluminate (MgAl ₂ O ₄ ), lanthanum oxide (La
₂ O ₃ ), copper oxide (CuO), bismuth oxide (Bi
₂ O ₃ ), nickel oxide (NiO), cobalt oxide (Co
2. The phosphor according to claim 1, which is at least one of O). 3. The method according to claim 2, wherein the fluoride having a positive charge is lithium fluoride.
(LiF), barium fluoride (BaF)_Two), Calcium fluoride
(CaF_Two), Magnesium fluoride (MgF_Two), Fluoride
Thorium (YF_Three), Lead fluoride (PbF_Two), Lanta fluoride
(LaF_Three), Dysprosium fluoride (DyF_Three), Fluorine
Zinc fossil (ZnF_Two), Manganese fluoride (MnF _Two Out of
The phosphor according to claim 1, wherein the phosphor is at least one of the following. 4. The phosphor according to claim 1, which has an average particle diameter in a range of 0.5 μm to 5.0 μm, a resin component comprising ethyl cellulose, terpineol, and butyl carbitol acetate. Or a phosphor ink containing a solvent component comprising pentanediol. 5. A method of forming a phosphor for applying a positively charged oxide or fluoride to a phosphor powder by using a nozzle for attaching or coating the same. 6. The positively charged oxides include magnesium oxide (MgO), zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ ), europium oxide (Eu ₂ O ₃ ), and neodymium oxide (Nd ₂ O). ₃ ) Dysprosium oxide (Dy ₂
O ₃ ), lead oxide (PbO), indium oxide (In)
₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), magnesium aluminate (MgAl ₂ O ₄ ), lanthanum oxide (La
₂ O ₃ ), copper oxide (CuO), bismuth oxide (Bi
₂ O ₃ ), nickel oxide (NiO), cobalt oxide (Co
6. The method for forming a phosphor according to claim 5, which is at least one of O). 7. The lithium fluoride having a positive charge is lithium fluoride.
(LiF), barium fluoride (BaF)_Two), Calcium fluoride
(CaF_Two), Magnesium fluoride (MgF_Two), Fluoride
Thorium (YF_Three), Lead fluoride (PbF_Two), Lanta fluoride
(LaF_Three), Dysprosium fluoride (DyF_Three), Fluorine
Zinc fossil (ZnF_Two), Manganese fluoride (MnF _Two Out of
6. The formation of the phosphor according to claim 5, which is at least one of the following.
Method. 8. The method for forming a phosphor according to claim 1, wherein the average particle diameter is 0.5 μm to 5.0 μm.
A phosphor ink containing a resin component comprising ethyl cellulose and a solvent component comprising terpineol, butyl carbitol acetate or pentanediol by means of a jet mill. A method for producing a phosphor ink having an ink viscosity of 15 to 200 centipoise. 9. The pressure of the mixed liquid at the time of mixing and dispersing by said jet mill is 10 kgf / cm ^{2 to} 100 kgf / c.
method for manufacturing a phosphor ink of claim 8 wherein the m ^2.