JP3448039B2 - Method for manufacturing plasma display panel and phosphor ink - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a plasma display panel, and more particularly to improvement of a phosphor ink and a phosphor coating apparatus used for forming a phosphor layer.

[0002]

2. Description of the Related Art In recent years, while expectations for high-definition and large-screen televisions such as high-definition television are increasing,
In the field of each display such as a CRT, a liquid crystal display (LCD) and a plasma display panel (Plasma Display Panel, hereinafter referred to as PDP), a display suitable for this is being developed.

The CRT, which has been widely used as a display for television from the past, is excellent in resolution and image quality, but it has a large screen of 40 inches or more because the depth and weight increase with the size of the screen. Is not suitable for. Further, the LCD has excellent performances of low power consumption and low driving voltage, but it is technically difficult to manufacture a large screen.

On the other hand, the PDP can realize a large screen with a small depth, and 50-inch class products have already been developed. PDPs are roughly classified into a direct current type (DC type) and an alternating current type (AC type) according to a driving method. Currently, the AC type, which is suitable for forming a panel having a fine cell structure, is mainly used. ing.

AC surface discharge type PDP, which is a typical AC type
In general, a front cover plate having display electrodes and a back plate having address electrodes are arranged in parallel with a gap so that both electrodes form a matrix, and the gap between the plates is a stripe. It is separated by a wall. And, in the groove between the partition walls, red,
The green and blue phosphor layers are formed and the discharge gas is filled in. When the discharge is applied by applying a voltage to each electrode in the drive circuit, ultraviolet rays are emitted, and the phosphor particles in the phosphor layer. (Red, green, blue) is designed to display an image by receiving this ultraviolet light and exciting and emitting.

In such a PDP, normally, partition walls are arranged on the back plate side, and a phosphor layer is formed in a groove between the partition walls.
It is manufactured by stacking a front cover plate on it and enclosing a discharge gas therein. By the way, as a method for forming the phosphor layer in the groove between the partition walls, Japanese Patent Application Laid-Open No. 6-520 is known.
As disclosed in Japanese Patent Laid-Open No. 5 (1994), a method of filling the phosphor paste in the grooves between the partition walls and baking the paste (screen printing method)
However, it is difficult to apply the screen printing method to a PDP having a fine cell structure.

For example, at the pixel level of a full-spec high-definition television, the number of pixels is 1920 × 1125, and the partition pitch (cell pitch) in the 42-inch class.
Is about 0.1 to 0.15 mm and the groove width between the partition walls is about 0.08 to 0.1 mm, which is very narrow, but since the phosphor ink used for screen printing has high viscosity ( It is usually tens of thousands of centipoise), and it is difficult to pour phosphor ink accurately and at high speed between such narrow partition walls. In addition, it is difficult to form a screen plate according to the PDP having such a fine structure.

In addition to the screen printing method, a photoresist film method and an ink jet method have been developed as a method for forming the phosphor layer. In the photoresist film method, as disclosed in JP-A-6-273925, a film of an ultraviolet photosensitive resin containing phosphors of each color is embedded between partition walls to form a phosphor layer of the corresponding color. This is a method of exposing and developing only a portion to be formed and washing away an unexposed portion. According to this method, even if the cell pitch is small, it is possible to bury the film between the partitions with a certain degree of accuracy.

However, since it is necessary to sequentially perform film embedding, exposure and development, and washing off for each of the three colors, there are problems that the manufacturing process is complicated and that color mixing is likely to occur, and the phosphor is relatively expensive. In addition, it is difficult to collect the washed-out phosphor, which causes a problem of high cost. On the other hand, the ink jet method
JP-A-53-79371 and JP-A-8-16201
As disclosed in Japanese Patent Publication No. 9, a method of applying a phosphor ink in a desired pattern on an insulating substrate by scanning an ink liquid consisting of a phosphor and an organic binder under pressure and ejecting from a nozzle. is there. In the ink jet method, ethyl cellulose, acrylic resin, polyvinyl alcohol, or the like is used as an organic binder, and terpineol or butyl carbitol acetate is used as a solvent,
A phosphor ink prepared by dispersing a phosphor in a mixture of an organic binder and a solvent using a disperser such as a paint shaker is generally used.

According to such an ink jet method, it is possible to accurately apply the ink to the groove between the narrow partition walls, but since the ejected ink becomes droplets and adheres intermittently, It is difficult to apply smoothly along the grooves between the partition walls arranged in stripes. In this regard, Japanese Patent Application No. 8-245853 previously filed by the present inventors
As disclosed in Japanese Patent Application No. Hei 9-253749 or Japanese Patent Application No. 9-253749, if a fluorescent ink with low viscosity and good fluidity is pressed and continuously jetted from a nozzle, it can be applied smoothly. Is.

[0011]

However, even when the phosphor ink is applied by this method, the finished P
When the DP is driven, streak-like unevenness is likely to occur along the partition wall, or streak-like unevenness is likely to occur along the cuts of the address electrodes, and there is a problem that the streak-like unevenness is particularly noticeable when white display is performed. It is considered that the reason why such streak-like unevenness occurs is that the phosphor layer formed in each groove has some variation or color mixture. Then, the following factors can be cited as factors that cause variations.

(1) When the phosphor ink is applied, a charge is generated in the phosphor ink, and the amount of charge generated due to the working environment and working conditions is easily influenced. Is easy to change from place to place. (2) When the phosphor inks of the three colors RGB are sequentially applied one by one, when the phosphor inks of the second and third colors are applied, the previously applied phosphor ink is applied to the adjacent groove. However, since it is affected by the rheology of the adjacent phosphor ink, the adhered state of the applied phosphor ink is unlikely to be constant.

It should be noted that this rheological effect can be eliminated if the next color is applied after being sufficiently dried each time one color is applied, but in that case, the number of drying steps increases, so that In addition to the equipment, the production process becomes complicated. (3) When applying the phosphor ink to the grooves between the partition walls, in order to apply it uniformly, it is desirable to scan so that the nozzle is always located at the center of the groove between the partition walls. Even if scanning is performed quickly, if the widths of the grooves between the partition walls are varied or the grooves are curved, the nozzle may be displaced from the central portion of the groove, so that it is difficult to uniformly apply the liquid. Especially in the case of a fine cell structure, this is likely to be a problem.

(4) When the fluorescent ink having a good fluidity is ejected from the fine nozzles, the ejection amount and the direction of the ejected jet are changed when the ejection from the nozzle is turned on and off. , It is difficult to fill the partition wall with the phosphor ink accurately. As yet another problem, generally, the phosphor ink applied to the grooves between the barrier ribs is difficult to adhere to the barrier rib side portions and tends to adhere to the groove bottoms in large numbers. It is difficult to form a well-balanced phosphor layer. Further, if the partition wall side portion of the phosphor layer and the groove bottom portion are not well balanced, there is a problem that it is difficult to obtain high panel brightness.

Further, since the nozzle diameter used in the ink jet method needs to be set narrow according to the partition wall interval, the nozzle is likely to be clogged and it is difficult to apply the phosphor continuously for a long time. There is also. In particular,
When manufacturing a high-definition PDP having a partition wall pitch of 0.15 mm or less, it is necessary to set the nozzle diameter to be considerably smaller than this, and therefore the problem of clogging is likely to occur.

In view of the above problems, the present invention can apply the phosphor ink continuously for a long time, and even in the case of a fine cell structure, the phosphor layer can be easily and accurately and uniformly formed. PROBLEM TO BE SOLVED: To provide a PDP manufacturing method capable of forming a PDP, and an ink coating device and a phosphor ink suitable for the PDP manufacturing method, thereby making it possible to display a PDP with a high image quality at a high brightness and with less streaks. The purpose is to be able to.

[0017]

Therefore, according to the present invention,
While applying the phosphor ink continuously from the nozzles, when the phosphor ink is applied by relatively scanning along the groove between the partition walls arranged on the plate, based on the positional information on each groove It was performed while adjusting the position in the groove through which the nozzle passes.

As a result, even if the groove is curved, the nozzle can always scan so as to pass through the center of the groove, so that the fluorescent ink is uniformly applied to each groove, and It can be attached to the bottom in the groove and the side surface of the partition wall in a well-balanced manner. In addition, in the present invention, while the phosphor ink is continuously discharged from the nozzle, when the phosphor ink is applied by relatively scanning along the groove between the partition walls arranged on the plate, each groove is applied. Was measured over the longitudinal direction of the groove, and the phosphor ink was ejected from the nozzle while adjusting the amount of the phosphor ink applied per partition wall length according to the measured groove width. As a result, the phosphor ink can be uniformly applied even when the groove width varies or the width varies in the groove.

Further, according to the present invention, when the phosphor ink is sequentially applied to the plurality of grooves, the state where the phosphor ink is continuously ejected from the nozzle is maintained even when the nozzle is off the groove. While applying. As a result, it is possible to prevent the fluorescent ink from adhering to the vicinity of the nozzle outlet, and thus to obtain a stable ink jet flow. Therefore, the phosphor ink can be uniformly applied to the plurality of grooves.

Further, in the present invention, the ink is redispersed by the disperser before the phosphor ink is continuously discharged from the nozzle. This also improves the dispersibility of the applied phosphor ink, so that the phosphor ink can be attached to the bottom of each groove and the side wall of the partition wall in a well-balanced manner. Further, in the present invention, in the phosphor ink used for the production of PDP, phosphor powder having an average particle size of 0.5 to 5 μm, terpineol, butyl carbitol acetate, butyl carbitol, which is a solvent having an OH group at the end, pentanediol, with a mixed solvent of limonene, as a binder, an ethoxy group in the cellulose molecule (-OC ₂ H ₅₎ content of 49% or more of ethyl cellulose (hydroxyl in the cellulose molecule (-OH) is ethoxy group Substituted) or ethylene oxide polymer was used, and a dispersant was further added. Here, the ethoxy content is the content of ethoxy groups in the cellulose molecule. For example, when the hydroxyl groups of cellulose are completely replaced by ethoxy groups, the ethoxy group content is 54. 88%.

The viscosity of the phosphor ink is preferably set to a low viscosity of 2000 centipoises or less (preferably 10 to 500 centipoises). In phosphor inks for PDPs, ethylcellulose-based, acrylic-based, and polyvinyl alcohol-based resins have been conventionally used as binders, and solvents such as terpineol and butyl carbitol have also been used, but generally binders are used. There is a problem that it is difficult to dissolve sufficiently in a solvent and it is difficult to improve the dispersion state of the phosphor particles and the resin.

On the other hand, by defining the type of binder and the type of solvent used in the phosphor ink as described above, the solubility of the binder in the solvent is improved and the dispersibility of the phosphor is enhanced. As a result, the phosphor ink filled in the grooves between the partition walls adheres well to the side walls of the partition walls, and the rheological effect of the adjacent phosphor ink is less likely to appear. Therefore, the phosphor ink can be attached to the bottom of each groove and the side surface of the partition wall in a well-balanced manner.

Examples of preferred dispersants added to the phosphor ink are anions selected from fatty acid salts, alkylsulfuric acid, ester salts, alkylbenzene sulfonates, alkylsulfosuccinates and naphthalene sulfonic acid polycarboxylic acid polymers. Nonionic surfactants selected from polyoxyethylene alkyl ethers, polyoxyethylene derivatives, sorbitan fatty acid esters, glycerin fatty acid esters and polyoxyethylene alkylamines, or alkylamine salts, A cationic surfactant selected from quaternary ammonium salts, alkyl betaines and amine oxides can be mentioned.

Further, in the present invention, a discharging substance is added to the phosphor ink for PDP production.
As a result, even in the case of a PDP having a fine structure, the phosphor ink can be uniformly applied to the grooves between the partition walls, and even when the completed PDP is driven, streaking hardly occurs. This is considered to be because the addition of a charge-eliminating substance or a dispersant to the phosphor ink prevents electrification when the phosphor ink is applied, and thus suppresses the rise of the phosphor ink and the like.

Examples of the static eliminator include conductive fine particles such as carbon fine particles, graphite fine particles, metal fine particles, and metal oxide fine particles, and various kinds of surface active agents listed above as the dispersants. Furthermore,
If the charge-eliminating substance to be added has the property of disappearing from the phosphor layer during firing or the property of losing its conductivity, such as a surfactant or carbon fine particles, the charge-eliminating substance remains in the phosphor layer. By doing so, there is no possibility that the PDP drive will be hindered.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] [Overall Structure and Manufacturing Method of PDP] FIG. 1 is a perspective view showing an AC surface discharge PDP according to an embodiment, and FIG. It is a block diagram of the display device which mounted the circuit block.

This PDP has a front panel 10 in which a discharge electrode 12 (scan electrode 12a, sustain electrode 12b), a dielectric layer 13, and a protective layer 14 are arranged on a front glass substrate 11.
And the rear panel 20 in which the address electrodes 22 and the dielectric layer 23 are arranged on the rear glass substrate 21, the electrodes 12a, 1
2b and the address electrode 22 are opposed to each other and are arranged in parallel with each other. The gap between the front panel 10 and the rear panel 20 is partitioned by the partition wall 30 in a stripe shape to form a discharge space 40, and the discharge space 40 is filled with a discharge gas.

In the discharge space 40, a phosphor layer 31 is arranged on the rear panel 20 side. The phosphor layers 31 are repeatedly arranged in the order of red, green and blue. The discharge electrodes 12 and the address electrodes 22 are both stripe-shaped, and the discharge electrodes 12 are arranged in a direction orthogonal to the barrier ribs 30 and the address electrodes 22 are arranged in parallel with the barrier ribs 30.

As shown in FIG. 2, each discharge electrode 12
The address electrodes 22 are divided at the center of the panel so that they can be driven by a dual scan method. The discharge electrode 12 and the address electrode 22 may be formed of a single metal such as silver, gold, copper, chromium, nickel, and platinum, but the discharge electrode 12 is formed of a conductive metal oxide such as ITO, SnO ₂ , and ZnO. It is preferable to use a combination electrode in which a thin silver electrode is laminated on a wide transparent electrode made of a material in order to secure a wide discharge area in the cell.

Then, the discharge electrode 12 and the address electrode 22
In the panel structure, cells that emit red, green, and blue colors are formed at the intersections of the two. Dielectric layer 13
Is a layer made of a dielectric material, which is disposed so as to cover the entire surface of the front glass substrate 11 on which the discharge electrodes 12 are disposed,
Generally, lead-based low-melting glass is used, but it may be formed of bismuth-based low-melting glass or a laminate of lead-based low-melting glass and bismuth-based low-melting glass.

The protective layer 14 is made of magnesium oxide (Mg
It is a thin layer of O) and covers the entire surface of the dielectric layer 13. The dielectric layer 23 is mixed with TiO ₂ particles so that it also functions as a visible light reflecting layer. The partition 30 is made of a glass material and is provided on the surface of the dielectric layer 23 of the rear panel 20 so as to project.

(Method for manufacturing PDP) A method for manufacturing this PDP will be described below. Preparation of front panel: The front panel is the front glass substrate 11
A discharge electrode 12 is formed on top of which a lead-based dielectric layer 1 is formed.
It is formed by covering the surface of the dielectric layer 13 with the protective layer 14 and covering the surface with the protective layer 14. The discharge electrode 12 is an electrode made of silver, and is formed by applying a silver paste for the electrode by a screen printing method and baking it. The discharge electrode 12 can also be formed by an ink jet method or a photolithography method.

The dielectric layer 13 is, for example, 70% by weight of lead oxide [PbO], 15% by weight of boron oxide [B ₂ O ₃ ], 1
0% by weight of silicon oxide [SiO ₂ ] and 5% by weight of aluminum oxide and an organic binder [1 to α-terpineol
520% of a mixture of 0% ethyl cellulose] was applied by a screen printing method, and then 520
A film having a thickness of about 20 μm is formed by baking at 20 ° C. for 20 minutes.

The protective layer 14 is made of magnesium oxide (Mg
O), and is generally formed by a sputtering method, but here, it is 1.0 μm by the CVD method.
To a film thickness of. The formation of the magnesium oxide protective layer by the CVD method is performed by setting a front glass substrate in a CVD apparatus and feeding a magnesium compound and oxygen as a source into the front glass substrate for reaction. Specific examples of the source used here include acetylacetone magnesium [Mg (C ₅ H ₇ O ₂ ) ₂ ] and cyclopentadienyl magnesium [Mg (C ₅ H ₅ ) ₂ ].

Preparation of rear panel: On the rear glass substrate 21, the screen printing method was used in the same manner as for the discharge electrode 12.
The address electrode 22 is formed. Next, a glass material mixed with TiO ₂ particles is applied by a screen printing method and baked to form the dielectric layer 23.

Next, the glass material is repeatedly applied by the screen printing method, and then the partition walls 30 are formed by baking. Then, the phosphor layer 31 is formed in the groove between the partition walls 30. A method of forming the phosphor layer 31 will be described in detail later, but the phosphor ink is applied by a method of scanning along the groove while continuously ejecting the phosphor ink from the nozzle, and after the application, the phosphor ink is applied. It is formed by baking to remove the solvent and the binder contained in.

When the material of the partition 30 is selected, the contact angle of the phosphor ink with respect to the side surface of the partition wall 30 is selected so that the phosphor is deposited on the side surface of the partition wall when the phosphor ink is dried. However, it is preferable to select one that is smaller than the contact angle with respect to the bottom surface of the groove. Also,
In this embodiment, the height of the partition wall is 0.1 to 0.15 according to the VGA of 40 inches and the high definition television.
mm, and the partition wall pitch is 0.15 to 0.36 mm.

Fabrication of PDP by panel bonding: Next, the front panel and the rear panel thus fabricated are bonded together by using sealing glass, and the inside of the discharge space 40 partitioned by the partition walls 30 is exposed to a high vacuum ( For example, 8 × 10 ^-7 To
rr) and then discharge gas (eg He-Xe system,
A PDP is produced by enclosing a Ne—Xe-based inert gas) at a predetermined pressure.

In this embodiment, the content of Xe in the discharge gas is 5% by volume or more, and the filling pressure is 500-.
Set in the range of 800 Torr. When the PDP is driven and displayed, a circuit block is mounted as shown in FIG. 2 to drive the PDP. [Explanation of Phosphor Ink, Ink Coating Device and Coating Method] In the phosphor ink, phosphor particles of each color are dispersed in a mixture of a binder, a solvent, a dispersant and the like to have an appropriate viscosity.

As the phosphor particles, those generally used in the phosphor layer of PDP can be used.
Specific examples thereof include: blue phosphor: BaMgAl ₁₀ O ₁₇ : Eu ²⁺ green phosphor: BaAl ₁₂ O ₁₉ : Mn or Zn ₂ S
iO _4: Mn Red _{phosphor: (Y x Gd 1-x} ) BO 3: Eu 3+ or Y
BO ₃ : Eu ³⁺ may be mentioned.

A detailed description of the composition of the phosphor ink will be given later. FIG. 3 is a schematic configuration diagram of an ink application device 50 used when forming the phosphor layer 31. Figure 3
As shown in FIG. 5, in the ink application device 50, an ink server 51 that stores phosphor ink, and an ink server 51.
A pressurizing pump 52 for pressurizing and sending out the phosphor ink inside,
A substrate mounting table 5 on which a nozzle head 53 that discharges the phosphor ink sent from the pressure pump 52 and a substrate (the rear glass substrate 21 on which the stripe-shaped partition walls 30 are formed) are mounted.
6. Rear glass substrate 21 mounted on the substrate mounting table 56
A groove placement detection head 55 for detecting the position of the groove 32 (between the partition walls 30) is provided.

In the ink coating device 50, the rear glass substrate 21 has the partition wall X on the substrate mounting table 56 in the figure.
It is arranged along the axial direction. In addition, the nozzle head 5
3 and the groove detection head 55 are provided with a drive mechanism (not shown) that drives them relative to the substrate mounting table 56, and in accordance with an instruction from the controller 60, the X axis along the surface of the substrate mounting table 56. Direction and the Y-axis direction. As the drive mechanism, a feed screw mechanism, a linear motor, or an air cylinder mechanism used in a triaxial robot or the like is used to drive the nozzle head 53 and the groove detection head 55, or the substrate mounting table 56. Just do
A specific example thereof will be described in Embodiment 2.

The substrate mounting table 5 of each head 53, 55
A position detecting mechanism (not shown) for detecting the position in the X-axis / Y-axis direction, that is, the (X, Y) coordinate on 6, is provided, and the controller 60 can detect these coordinate positions. A linear sensor may be provided as the position detecting mechanism. For example, in an X-axis or Y-axis driving mechanism,
When using a drive source such as a pulse motor that can accurately control the drive amount, if a reference position detection sensor that can detect the reference position of the X-axis or the Y-axis is provided, the drive can be performed. From the drive amount of the source to the X-axis or Y
Axial position can be measured.

The nozzle head 53 is integrally formed by machining and discharging a metal material, including the ink chamber 53a and the nozzle 54.
The phosphor ink supplied from the pressurizing pump 52 is temporarily stored in the ink chamber 53a and jets an ink jet continuously from the nozzle 54. Here, it is assumed that the nozzle head 53 is provided with only one nozzle 54, but it is also possible to provide a plurality of nozzles 54 to eject a plurality of ink jets. At 53a, the phosphor ink is distributed and the pressure applied to each nozzle is made uniform. The diameter of the nozzle 54 is preferably set to be considerably smaller than the partition wall pitch in consideration of preventing the ink jet from protruding from the groove between the partition walls as described later with reference to FIG. It is also necessary not to cause clogging. Normally, it is set in the range of several tens to several hundreds of μm,
This also changes depending on the conditions such as the discharge amount of the phosphor ink.

In addition, the ink server 51 is provided with a stirrer 51a in order to prevent particles (phosphor particles and the like) in the stored phosphor ink from settling. The groove detection head 55 is scanned along the surface of the rear glass substrate 21 mounted on the substrate mounting table 56, and the characteristics at each position on the surface (for example, the amount of light reflected from the surface,
The surface permittivity and the like) are measured, and the position information of each groove 32 on the rear glass substrate 21 can be obtained based on the measurement result of the groove detection head 55.

Here, as shown in FIG. 3, the groove detecting head 55 has a CCD line sensor 57 extending in the Y-axis direction and light reflected from the upper surface of the rear glass substrate 21 on the CCD line sensor 57. The image forming lens 58 is provided, and the image data of the upper surface of the rear glass substrate 21 corresponding to the width of the CCD line sensor 57 in the Y-axis direction is taken in and sent to the controller 60.

[Explanation of Groove Position Detection and Ink Application Operation by Ink Application Device 50] Such an ink application device 5
0 is used to obtain the position information of the grooves 32a, 32b, 32c between the partition walls 30, and the position of the nozzle head 53 in the groove is controlled on the basis of the position information so as to apply the phosphor ink of each color to the grooves 32a, 32b, 32c. In order. The specific examples are shown below.

First, the rear glass substrate 21 is placed on the substrate platform 56, and the operation of imaging the groove detection head 55 while scanning in the X-axis direction is repeatedly performed while shifting in the Y-axis direction. , The image data over the entire surface of the rear glass substrate 21 is sequentially sent to the controller 60. The controller 60 takes in the image data sent from the groove detection head 55 and stores the image data in which the coordinates on the substrate mounting table 56 and the brightness are associated with each other in the memory.

FIG. 4 schematically shows the image data thus obtained. In the figure, the shaded portion corresponds to the rear glass substrate 21, and the white portion in the shaded portion is the partition wall 30. It is a portion corresponding to the upper surface. Next, a scan line is set based on the obtained image data. In the image data, the grooves 32a, 32b, 32c between the partition walls 30 are distinguished from each other by the hatched display and the blank display in FIG.
Since it is considered that the portion corresponding to (1) and the portion corresponding to the upper surface of the partition wall 30 have different brightness levels (generally, the groove portion is dark because the amount of light reflected is smaller than that of the partition wall upper surface portion). If the location where the brightness level changes abruptly is regarded as the edge of each groove 32a, 32b, 32c (the boundary line between the groove and the partition wall), and the scanning line S is set in the middle of both edges in each groove 32a, 32b, 32c. Good.

The method of setting the scanning line S will be described more specifically below. In the image data of FIG. 4, a plurality of search lines L are drawn at equal pitches in parallel with the Y axis so as to cross the partition wall 30. FIG. 5A is a partially enlarged view of FIG. 4, in which search lines L1, L2, L3 ... L6 are shown.
Is drawn.

FIG. 5 (b) is a graph schematically showing the luminance at each position on the search line L1.
High brightness at the position corresponding to the upper surface of the groove 32a, 32b,
It is shown that the brightness is low at the position corresponding to 32c. On the search line L1 in FIG. 5A, points (P11, P12, P13, ...
The Y coordinate of P18), that is, the rising and falling Y coordinates in the graph of FIG. Similarly, for the search lines L2, L3, ... L6 in FIG. 5A, the brightness change points (P21, P22, P) at which the brightness changes abruptly.
23, ..., P28), brightness change points (P31, P32, P33, ...,
P38), ... Luminance change point (P61, P62, P63, ..., P68)
The Y coordinate of is calculated.

The middle point Q1 of the brightness change points P11 and P12
1, the midpoint Q21 of the brightness change points P21 and P22, ..., The coordinates of the midpoint Q61 of the changes P61 and P62 are obtained, and the midpoint Q11, the midpoint Q21 ,.
By connecting the middle points Q61, the scanning line S1 for the groove 32a at the left end of FIG. 5A is set. Figure 5
Similarly, for the second, third, and fourth grooves from the left in (a), the scan lines S2, S3, and S4 are set by connecting the coordinates of the midpoints of the brightness change points.

After the scanning line S is set in this way, the fluorescent inks of the respective colors are ejected from the nozzles 54 while scanning the nozzles 54 along the respective scanning lines, so that the fluorescent inks are introduced into the grooves 32a, 32b, 32c. Apply. Specifically, it is performed as follows. First, the ink server 51
Put the first color (for example, blue) phosphor ink among blue, green, and red.

The controller 60 moves the nozzle head 53 to the end of the scanning line S of the groove 32a to be applied first, and drives the pressure pump 52 to pressure-feed the phosphor ink. As a result, the phosphor ink is ejected as a continuous flow from the nozzle 54. The distance between the lower end of the nozzle 54 and the upper surface of the partition wall is usually set to 0.5 to 3 mm, although it depends on conditions such as the ink discharge amount.

In this state, the controller 60 scans the nozzle head 53 in the X direction, but the nozzle 54 scans the scan line S.
The nozzle head 53 is also scanned while adjusting the position of the nozzle head 53 in the Y direction. The controller 60 then controls the nozzle head 5
3 is shifted in the y-axis direction, and the groove 32 to be applied next is
The nozzle head 53 is moved to the end of the scanning line S of a, and the rear glass substrate 21 is scanned at a high speed in the opposite direction while discharging the phosphor ink from the nozzle, so that the nozzle 54 is aligned with the scanning line S. Phosphor ink is applied while scanning the nozzle head 53. Then, by repeating such an operation, the first color phosphor ink is applied to all the grooves 32a in the rear glass substrate.

Next, in the same manner, in the adjacent groove 32b,
A second color (for example, green) phosphor ink is applied, and a third color (for example, red) phosphor ink is applied to the adjacent groove 32c. As a result, three colors of phosphor ink are applied to the grooves 32a, 32b, 32c. According to the above-described phosphor ink application method, even if the grooves 32a, 32b, 32c are inclined with respect to the X axis as shown in FIG. 6A, or as shown in FIG. 6B. So groove 32
Even if a, 32b, and 32c are curved, the scanning line S is set so as to always pass through the center of each groove, and the nozzle 54 is scanned along the scanning line S, so that the phosphor ink is always The phosphor ink is applied to the side walls of the partition walls on both sides of the groove, and the phosphor ink is uniformly applied along the groove.

That is, when the grooves 32a, 32b, 32c are inclined or curved with respect to the X axis as shown in FIGS. 6 (a) and 6 (b), the nozzle 54 should be moved in the Y axis direction. If scanning is performed linearly in parallel with the X axis, the nozzle 54 is displaced from the central portion of the groove 32 and approaches one of the partition walls (left side in FIG. 7) 30 as shown in FIG. 7A. There are places, and in such places, a large amount of phosphor ink is likely to adhere to the side wall surface of the near side, and the formed phosphor layer is also formed on the side wall surface of one side, as shown in FIG. 7B. It is easily formed thick. And in extreme cases, nozzle 5
There is a possibility that 4 will be out of the groove and mixed. On the other hand, if the coating method of the present embodiment is used, the phosphor ink is evenly coated on both side surfaces at any location.

Even if the nozzle does not necessarily scan directly above the set scanning line, such an effect can be obtained if the nozzle is scanned not too far from each scanning line. (Regarding control of discharge amount of phosphor ink) If the pitch of the partition walls 30 is constant and the groove widths of the grooves 32a, 32b, 32c are uniform, the nozzle scanning speed and the ink discharge amount (per unit time). The discharge amount from the nozzle) may be set to a constant value, but if the groove width varies or the width changes in the groove, the nozzle scanning speed and the ink discharge amount should be constant. , The adhesion state of the phosphor ink (balance of adhesion to the bottom and side surfaces of the groove) becomes uneven. This is because the area where the groove width is wide is smaller than the area where the groove width is narrow because the phosphor ink to be applied is dispersed over a wider area, so that the phosphor ink is less applied to the side surfaces of the partition walls.

Further, when the groove width is small, the applied amount of the phosphor ink may be too large, and the adjacent grooves may overflow to cause color mixing. On the other hand, as described below, it can be solved by adjusting the pressure for pressing the phosphor ink by controlling the discharge amount or by controlling the scanning speed according to the fluctuation of the groove width. In the image data of FIG. 4, on the search line L, the grooves 32a, 3
The groove width for each of 2b and 32c is measured, and when ink is applied by scanning the nozzle 54, the ink application amount per unit length in the X-axis direction is proportional to the groove width based on the measurement. The pressure of the pressurizing pump 52 or the drive speed of the X-axis drive mechanism is controlled.

For example, for the scanning line S1 of FIG. 5A, the groove width at the point Q11 (distance between points P11 and P12), the groove width at the points Q21, ... Q61 are measured.
Then, when scanning the scan line S1 with the nozzle 54,
When the nozzle 54 passes over the points Q11, Q21, ... Q6, the pressure applied by the pressurizing pump 52 is made proportional to the groove width measured above.

By controlling in this manner, the amount of phosphor ink applied per unit length in the X-axis direction is substantially proportional to the groove width, so that even if the groove width varies or fluctuates, The phosphor ink adheres uniformly, and color mixing does not occur even when the groove width is small. In this embodiment, a groove detection head 55 takes an image of the entire upper surface of the rear glass substrate 21, and the groove position information is obtained from the image data. However, the method of setting the scan line by using the above is shown, but the method of setting the scan line is not limited to this, and there are various methods.

For example, the brightness change point can also be obtained by scanning a head having a CCD line sensor extending in the X-axis direction in the Y-axis direction so as to cross the partition wall 30. That is, by detecting the brightness on the lines corresponding to the search lines L1, L2 ... In FIG. 5A, the brightness change point can be similarly obtained and the scanning line can be set.

Further, in the above-mentioned embodiment, the point where the brightness changes abruptly is detected and judged as the edge of the groove. However, for example, a distance sensor is arranged in the groove detecting head 55, Similarly, it is also possible to scan the upper surface of the rear glass substrate 21 and detect a point at which the distance from the distance sensor suddenly changes, and determine it as the groove edge. Alternatively, a dielectric measuring sensor for measuring the dielectric constant is arranged on the groove detecting head 55, and the upper surface of the rear glass substrate 21 is similarly scanned,
It is also possible to detect the point at which the dielectric changes sharply and determine it as the groove edge.

Further, in the ink coating device 50, the nozzle head 53 and the groove detecting head 55 can be driven independently of each other. However, even if these are integrally driven, the same operation as described above is performed. Can be done. In the ink coating device 50, the groove detection head 55 is previously formed over the entire upper surface of the rear glass substrate 21.
Although the example in which the position of the groove is detected to set the scanning line and the application of the phosphor ink is started after that, it can be performed in parallel. That is, while scanning the nozzle head 53 and applying phosphor ink, image data is obtained for a groove to which ink is to be applied later, and a scan line is set, and the scan line is applied when ink is applied to the groove. It is also possible to perform scanning while controlling the nozzle head 53 in accordance with the above.

That is, if the scanning line is set prior to scanning the nozzle head 53, the nozzle head 53 can be controlled accordingly, and it is considered that the same effect as that of the above-described embodiment can be obtained. . Therefore, for example, a groove detector (CCD line sensor) for detecting the center position of the groove in front of the scanning direction is attached to the nozzle head 53, and when the nozzle head 53 is scanned, the nozzle is detected by the groove detector. It is also possible to detect the center position of the groove prior to the head 53 and perform scanning while controlling the nozzle head 53 so as to pass through the detected center position. However, in this case, it is necessary to detect the center position of the groove and drive in the y-axis direction quickly.

In addition to this, a nozzle detector is attached to the nozzle head 53, the positional deviation between the nozzle and the central position of the groove detected by the groove detector is calculated, and the nozzle head 53 is eliminated so as to eliminate the positional deviation. It is also possible to perform a feedback correction in which is driven in the y-axis direction. Further, in the above-described embodiment, the case where one nozzle 54 is provided in the nozzle head 53 has been described, but the same can be performed when a plurality of nozzles 54 is provided in the nozzle head 53.

In this case, each nozzle 54 is scanned while adjusting the nozzle head 53 in the Y-axis direction along each scanning line. For example, the nozzle pitch is set to three times the partition wall pitch, and the position of the nozzle head 53 is adjusted by averaging the scan lines set at the center of each groove 32a as the scan line of the nozzle head 53. Scanning is performed while adjusting the nozzle head 53 in the Y-axis direction so as to match the scanning line.

This makes it possible to apply the phosphor ink in parallel to a plurality of grooves. If the number of nozzles 54 provided in the nozzle head 53 is one, the groove 3
Although the number of times of tact is required by the number of 2a, 32b, 32c, the number of times of tact can be reduced by increasing the number of nozzles 54 provided in the nozzle head 53 as described above. For example, if the nozzle head 53 is provided with the three nozzles 54, it is possible to apply the liquid to the three grooves in one scanning, and it is needless to say that the number of tact can be reduced to 1/3.

In a high definition PDP, the rear glass substrate 21
The number of the grooves 32a, 32b, 32c provided in is very large at several hundreds to several thousands (for example, 16:
The 9 type VGA level PDP display device has about 850 grooves for each color, and the HD type has 1920 grooves for each color). Therefore, the working efficiency can be considerably improved by increasing the number of nozzles 54.

In the present embodiment, the method of applying the next color after the application of the first color phosphor ink has been described, but the ink applying device 50 is provided with nozzle heads for three colors. It is also possible to apply three colors of phosphor ink in parallel. [Composition of phosphor ink] (1) In order to prevent clogging of the phosphor particle nozzle and precipitation of the phosphor particles, the average particle diameter of the phosphor particles used in the phosphor ink is 5
It is preferable that the thickness is less than or equal to μm. Further, in order for the phosphor to obtain good luminous efficiency, the average particle size of the phosphor is preferably 0.5 μm or more. Therefore, it is preferable to use the phosphor particles having an average particle diameter of 0.5 to 5 μm, particularly 2 to 3 μm.
It is preferable to use those in the range of m.

Further, in order to improve the dispersibility of the phosphor particles, it is effective to adhere or coat an oxide or a fluoride on the surface of the phosphor particles as follows. Examples of metal oxides that are attached or coated on the surface of phosphor particles include magnesium oxide (M
gO), aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), indium oxide (InO ₃ ), zinc oxide (ZnO), and yttrium oxide (Y ₂ O ₃ ). Among them, SiO ₂ is known as a negatively charged oxide, while ZnO, Al ₂ O ₃ , and Y ₂ O ₃ are known as positively charged oxides. Alternatively, coating is effective.

The particle size of the oxide to be attached is considerably smaller than the particle size of the phosphor particles, and the amount of these oxides adhering to the surface of the phosphor particles is 0.05 to 0.05.
A range of 2.0% by weight is suitable. This is because if it is less than this range, the effect is small, and if it is too large, the vacuum ultraviolet rays generated in the plasma are absorbed and the panel brightness is reduced.

Magnesium fluoride (MgF ₂ ) and aluminum fluoride (AlF ₃ ) are examples of the fluoride attached or coated on the surface of the phosphor particles. (2) Binder As a binder suitable for favorably dispersing the phosphor particles, ethyl cellulose or polyethylene oxide (a polymer of ethylene oxide) may be mentioned.
Content of ethoxy group (-OC ₂ H ₅₎ is preferably used from 49 to 54% of ethylcellulose.

A photosensitive resin may be used as the binder. (3) Solvent As the solvent, it is preferable to use a mixture of an organic solvent having a hydroxyl group (OH group). Specific examples of the organic solvent include terpineol (C ₁₀ H ₁₈ O), butyl carbitol acetate, Pentanediol (2,2,4
-Trimethylpentanediol monoisobutyrate),
Examples include dipentene (also known as Limonen) and butyl carbitol.

The mixed solvent obtained by mixing these organic solvents is
It has excellent solubility to dissolve the above-mentioned binder and excellent dispersibility of the phosphor ink. The content of the phosphor in the phosphor ink is 35 to 60% by weight,
The content of the binder is appropriately within the range of 0.15% to 10% by weight. In addition, in order to adjust the shape of the phosphor ink applied to the groove as described later, it is preferable to set the binder content to a large value within a range in which the ink viscosity does not become too high.

(4) Dispersant By further adding a dispersant to the phosphor ink having the above composition, the dispersibility of the phosphor particles in the ink can be improved. Examples of the dispersant include the following surfactants. * Anionic surfactant: fatty acid salt, alkyl sulfuric acid, ester salt, alkylbenzene sulfonate, alkyl sulfosuccinate, naphthalene sulfonic acid polycarboxylic acid polymer.

* Nonionic surfactant: polyoxyethylene alkyl ether, polyoxyethylene derivative, sorbitan fatty acid ester, glycerin fatty acid ester,
Polyoxyethylene alkylamine. * Cationic surfactant: For example, alkylamine salt,
Quaternary ammonium salt, alkyl betaine, amine oxide.

(5) Static eliminator It is also preferable to add a static eliminator to the phosphor ink. The surfactants listed as the dispersants in (4) above also generally have a neutralizing action to prevent the phosphor ink from being charged, and many of them correspond to neutralizing substances. However, the phosphor,
Since the static elimination effect differs depending on the type of binder and solvent, it is recommended to test various types of surfactants and select the one with good results.

The amount of the surfactant added is from 0.05 to
0.3% by weight is suitable, and if it is less than this range, the dispersion improving effect or the charge eliminating effect cannot be expected so much. On the other hand, if it is more than this range, the luminance is affected, which is not preferable. Examples of the static elimination material include fine particles made of a conductive material, in addition to the surfactant.

The conductive fine particles include carbon fine powder such as carbon black, fine graphite powder, fine metal powder such as Al, Fe, Mg, Si, Cu, Sn and Ag, and metal oxides thereof. The fine powder is. The amount of such conductive particles added to the phosphor ink is preferably in the range of 0.05 to 1.0% by weight.

By adding a charge eliminating substance to the phosphor ink, the phosphor ink is prevented from being charged.
The following effects are produced in PDP production. There is a problem that streak unevenness is likely to occur when the manufactured panel is driven when the static elimination substance is not added to the phosphor ink, but the streak unevenness is caused by the addition of the static elimination substance to the phosphor ink. Can be suppressed.

Further, when the discharging material is not added to the phosphor ink, the problem that the phosphor layer rises up at the break (see FIG. 2) of the address electrode 22 in the central portion of the panel due to the charging of the phosphor ink tends to occur. But,
This can also be suppressed by adding a charge removing substance to the phosphor ink. These are caused by a slight variation in the amount of the phosphor ink applied to each groove and the state of adhesion to the groove when the phosphor ink (especially one using an organic solvent) is charged during application. It is considered that this charging is prevented by adding a charge eliminating substance to the ink.

Further, by suppressing the electrification, it is possible to prevent the color mixture due to the suitable dispersion of the liquid. Further, when a surface-active agent or carbon fine powder is used as the static elimination material as described above, the static elimination material is also evaporated or burned out in the phosphor firing step for removing the solvent or binder contained in the phosphor ink. Therefore, the static elimination material does not remain in the phosphor layer after firing. Therefore, there is no possibility that driving (light emitting operation) of the PDP will be hindered by the static elimination material remaining in the phosphor layer.

[Production Method of Phosphor Ink] The phosphor ink contains the above binder in an amount of 0.2 with respect to the solvent.
It is prepared by dissolving 10 to 10% by weight, mixing phosphor particles of each color therein, and dispersing the phosphor particles using a disperser. As a disperser for producing phosphor ink,
In addition to vibration mills and stirring tank type mills (ball mills, bees mills, sand mills, etc.) that disperse using balls, flow pipe type mills, jet mills that disperse without using balls,
Examples include nanomizer.

Balls of zirconia or alumina are used as a dispersion medium (media) of a vibration mill or a stirring tank type mill, and in particular, zirconia (ZrO ₂ ) having a diameter of 0.2 to ₂ mm is used.
It is preferable to use balls. This is for suppressing the damage to the phosphor powder and suppressing the contamination (contamination) of impurities. When using a jet mill, 10-
Dispersion is preferably carried out in the pressure range of 100 kgf / cm ² . This pressure range is preferably 10 kgf / cm
^If it is less than ² , sufficient dispersion cannot be obtained and 100 kgf / cm ²
This is because the phosphor particles tend to be crushed when it exceeds the range.

The viscosity of the phosphor ink (viscosity at 25 ° C. and a shear rate of 100 sec ⁻¹ ) is adjusted to 2000 centipoises or less, preferably 10 to 500 centipoises. A method of attaching an oxide or a fluoride to the surface of the phosphor particles is, for example, magnesium oxide (MgO), aluminum oxide (Al ₂
O ₃ ), silicon oxide (SiO ₂ ), indium oxide (InO
₃ ) or other metal oxide suspension, or magnesium fluoride (MgF ₂ ) or aluminum fluoride (AlF ₃ ) suspension of metal fluoride, and after mixing and stirring, suction filtration is performed. It can be performed by drying at a temperature of not less than 0 ° C and baking at 350 ° C. Here, in order to improve the adhesive force between the phosphor particles and the oxide or fluoride, a small amount of resin, silane coupling agent or water glass is added to the suspension. Good.

Further, for example, in order to coat the surface of the phosphor particles with a film of aluminum oxide (Al ₂ O ₃ ), Al (OC) which is an alkoxide of aluminum is used.
_This can be performed by adding phosphor particles to an alcohol solution of ₂ H ₅ ) ₃ and stirring the mixture. [Regarding the Effect of the Phosphor Ink of the Present Embodiment] As described above, the phosphor ink of the present embodiment has excellent dispersibility, and therefore, when applied to the grooves between the partition walls, the adhesion to the partition wall side surface is good. is there. The principle will be described below.

FIG. 8 is a diagram schematically showing how the phosphor layer is formed after the phosphor ink is applied to the grooves between the partition walls. When the phosphor ink having good fluidity is filled between the partition walls 30, the phosphor particles in the filled phosphor ink are
Gravity F1 works and tries to settle this to the bottom. on the other hand,
A force F2 for moving the phosphor particles in the phosphor ink in the lateral direction of the partition wall also acts. This force F2 is a force for pulling the phosphor particles, which are bound together by the binder, toward the partition wall as the solvent in the phosphor ink diffuses into the partition wall 30.

The shape of the phosphor layer finally formed in the groove between the partition walls is determined by the balance between these forces F1 and F2. The better the dispersibility of the phosphor ink, the stronger the force F2. Therefore, it is considered that the adhesion of the phosphor ink to the side surface of the partition wall is improved due to the large size. Also,
As described above, it is the same principle that it is preferable to set the content of the binder in the phosphor ink to a large value. Since the force F2 is improved by setting the content of the binder to a large value, Adhesion of the phosphor ink to the side surface of the partition wall is improved.

When the adhesion of the phosphor to the side wall of the partition wall is improved, the ratio of the phosphor layer formed on the side wall of the partition wall is increased, which contributes to the improvement of the panel brightness of the PDP. This is because the ultraviolet light generated near the display electrode can be efficiently converted into visible light. FIG. 9 schematically shows how the shape of the formed phosphor layer changes when the concentration of the resin binder in the phosphor ink is changed.

As shown in the figure, when the resin concentration is low, the phosphor particles almost settle to the bottom and the phosphor layer is formed only on the bottom. However, as the resin concentration component increases,
Since the binding force between the phosphor particles is increased, the amount of the phosphor adhered to the side surface of the partition wall is increased, and when the resin concentration component is higher than a certain level, the phosphor layer is formed only on the side surface of the partition wall.

In the case where the phosphor inks of a plurality of colors are applied to the grooves in order, when the phosphor inks of the second and third colors are to be applied, the phosphors are already formed in the adjacent grooves. Since the ink is applied, the partition walls are already permeated with the solvent. Therefore, the solvent in the phosphor ink newly applied to the groove hardly penetrates into the partition walls, and therefore, when the phosphor ink having poor dispersibility is used, the force F2 hardly acts.

However, when the phosphor ink having good dispersibility is used as in this embodiment, a certain amount of force F2 works even if the phosphor ink is applied to the adjacent groove as described above. The adhesion of the phosphor ink to the is relatively good. Further, the diameter of the nozzle 54 is usually set to be considerably smaller than the partition wall pitch, and in order to stably discharge the phosphor ink from the thin nozzle, the ink viscosity also needs to be set to be considerably low. As shown in FIG. 10, it is necessary to lower the viscosity by about two digits as compared with the ink viscosity used in the conventional screen printing.

Therefore, the nozzle is likely to be clogged, but since the phosphor ink of the present embodiment has good dispersion of the phosphor particles, the nozzle is less likely to be clogged, and therefore the phosphor ink is continuously extended. It is possible to apply for a time, and it is also possible to apply continuously for 100 hours or more.
The reason why the diameter of the nozzle 54 is set to be considerably smaller than the partition pitch is as follows.

FIG. 11 is a diagram showing the discharge state of the phosphor ink from the nozzle. As shown in FIG. 11A, there is a tendency for the phosphor ink to expand after the phosphor ink is ejected from the nozzle. This is the so-called ballast effect. Considering this point, the nozzle diameter d
Must be considerably smaller than the partition pitch.
For example, in the case of VGA class partition walls with a pitch of 360 μm,
It is necessary to set the nozzle diameter d to around 100 μm.
In the D class, it is necessary to set the nozzle diameter d to a very small value of around 50 μm.

(Modification of Method of Applying Phosphor Ink)
When such low viscosity phosphor ink is ejected from the nozzle and then the ejection is stopped, as shown in FIG. 11B, the axis of the jet flow is deviated in the flow after the stop, and the flow is likely to be unstable. . The reason for this is that when ink ejection is stopped, the fluorescent ink adheres to the periphery of the nozzle at the tip of the nozzle (bottom surface of the nozzle), and its wettability changes slightly. It is small, and it becomes remarkable when the viscosity of the ink is small.

As a countermeasure against this, the fluorescent ink may be continuously ejected from the nozzle 54 and continuously ejected while the plurality of grooves are successively coated. In other words, even when the nozzle 54 is out of the groove, if a coating method is used in which the discharge of the phosphor ink is continued without being stopped, it is possible to prevent the phosphor ink from adhering to the lower surface of the nozzle tip. The deviation of the axis of the ink jet jet as shown in b) can be prevented.

For example, if the phosphor ink is continuously ejected until the coating of one color is finished on the entire rear glass substrate 21, the axis deviation of the ink jet jet can be prevented during that period, so that the ink jet jet is stable. It can be applied. [Second Embodiment] FIG. 12 is a perspective view showing an ink applying apparatus according to the present embodiment, and FIG. 13 is a front view (partial cross section) of the ink applying apparatus.

This ink coating device has basically the same structure as the above-mentioned ink coating device 50, except that the circulation mechanism for collecting and using the phosphor ink and the nozzle head having a plurality of nozzles are rotated to change the nozzle pitch. The device is equipped with a nozzle rotation mechanism for adjustment. (Structure of Ink Application Device) This ink application device is composed of an apparatus main body 100 and a controller 200.

The apparatus main body 100 includes a main body base 101,
A substrate mounting table 103 that moves in the X-axis direction (the arrow X direction in the drawing) along a rail 102 laid on the upper surface of the main body base 101, and a rail 105 of an arm 104 provided so as to straddle the main body base 101. The nozzle head unit 110 moving along the Y-axis direction (the arrow Y direction in the drawing) along with the arm 104 moving in the Y-axis direction to move the substrate mounting table 103.
An image pickup unit 120 is provided for detecting the partition wall position of the rear glass substrate 21 placed on the top.

Inside the main body base 101, an X drive mechanism 1 for reciprocally driving the substrate mounting table 103 in the X-axis direction.
30 are provided. The X drive mechanism 130 includes a drive motor 131 (for example, a servo motor or a stepping motor), a feed screw 132 extending in the X axis direction along the rail 102, and a nut 133 fixed to the lower portion of the substrate platform 103. By rotating the feed screw 132 with the drive motor 131, the substrate mounting table 103 together with the nut 133 can be slid at high speed in the X-axis direction.

FIG. 14 is an enlarged view of the nozzle head unit 110 shown in FIG. Nozzle head unit 11
In 0, a drive base portion 111 having a built-in Y-axis drive mechanism for reciprocating the same in the Y-axis direction, a nozzle head 112 having a plurality of nozzles 113 arranged in parallel, and the heights of the nozzle heads 112 are adjusted. In order to raise and lower this, and the nozzle head 112, the substrate mounting table 103.
A rotary drive mechanism 115 for rotating and driving in a plane parallel to is provided.

As the Y-axis drive mechanism and the elevating mechanism 114, for example, a linear motor or a slide mechanism combining a drive motor with a pinion gear and a rack gear can be applied. Further, as the rotation driving mechanism 115, for example, a servo motor is used, and by this, the nozzle head 112 is rotated about the rotation shaft 112a. The image pickup unit 120 can be driven on the arm 104 in the Y-axis direction by a Y-axis drive mechanism (not shown) like the drive base section 111. The imaging unit 120 includes the groove detection head 5 described in the first embodiment.
As in the case of 5, the CCD line sensor extending in the Y-axis direction and the like are built in, and the upper surface image data of the rear glass substrate 21 placed on the substrate platform 103 can be obtained.

Although not shown in the drawing, this ink application device is provided with an X position detecting mechanism for detecting the position of the substrate mounting table 103 in the X axis direction, and positions of the nozzle head unit 110 and the image pickup unit 120 in the Y axis direction. A linear sensor (for example, an optical linear encoder) is provided in each of the X-axis direction, the Y-axis direction, and the vertical direction as a Y position detecting mechanism for detecting and a height detecting mechanism for detecting the height position of the elevating mechanism 114. Accordingly, in the controller 200, the positions of the nozzle head unit 110 and the imaging unit 120 (X coordinate and Y axis coordinate on the substrate mounting table 103) and the nozzle head 112 of the nozzle head 112 are detected based on the signals from the linear sensors. The height can be detected at any time.
Further, the angle θ of the nozzle head 112 with respect to the X axis can be detected at any time by an angle detection mechanism (for example, a rotary encoder).

The nozzle head 112 and the image pickup unit 120 are made by the driving mechanisms and the detection mechanisms as described above.
Can scan in the X-axis direction and the Y-axis direction along the substrate mounting table 103, and the nozzle head 112 can
The height from the substrate mounting table 103 and the angle with respect to the X axis can be adjusted. In addition, as shown in FIGS. 12 and 13, a suction pump 141 and the suction pump 141 and the substrate mounting table are provided inside the main body base 101 in order to configure the substrate suction mechanism 140 that sucks the substrate on the substrate mounting table 103. Flexible hose 14 for connecting with 103
Two are provided. A cavity 103a (see FIG. 13) is formed inside the substrate mounting table 103, and a large number of fine holes communicating with the cavity 103a are provided on the upper surface of the substrate mounting table 103. And suction pump 1
By evacuating the cavity 103a at 41, the substrate on the substrate platform 103 can be adsorbed.

As shown in FIGS. 12 and 13, the apparatus main body 10
In order to collect and circulate the phosphor ink ejected from the nozzle head unit 110, the circulation mechanism 1
50 are provided. The circulation mechanism 150 collects the phosphor ink (ink jet) ejected from the nozzle head unit 110, and the pressurizing pump 15 that pressurizes and ejects the phosphor ink in the collection container 151.
It is composed of 2 etc.

The recovery container 151 extends in the Y-axis direction so that the ink jet can be recovered over the entire scanning range of the nozzle head unit 110, and the recovered phosphor ink passes from the pressure pump 152 through the pipe 153. Are supplied to the nozzle head 112 in the nozzle head unit 110 and are circulated for use. Further, the circulation mechanism 150 is provided with an ink replenisher 154 for keeping the amount of circulating phosphor ink constant.
The ink replenisher 154 monitors whether or not the amount of ink in the recovery container 151 is equal to or more than a specified amount, and automatically replenishes the phosphor ink when the amount of ink is equal to or less than the specified amount.

Further, in order to prevent the ink jet ejected from the nozzle head 112 from adhering to the end portion of the rear glass substrate 21, a jet shield mechanism 116 is provided in the nozzle head unit 110. The jet shield mechanism 116 includes a shield tray 117 that slides in the X-axis direction and a solenoid (not shown) that slides and drives the shield tray 117. The shield tray 117 normally retracts from the ink jet passage line. It is possible to slide to a position where the ink jet is blocked by driving the.

The phosphor ink shielded by the shield tray 117 is transferred to the second recovery container 118 by a suction pump (not shown). The controller 200 is
The drive control of each unit of the apparatus main body 100 is performed. The controller 200 includes a drive motor 131, a nozzle head unit 110, an image pickup unit 120, a suction pump 141, a pressure pump 152, and cables 201 to 20.
These units are driven by electric power and drive control signals supplied from the controller 200 through each cable.

The image data obtained by the image pickup unit 120 is sent to the controller 200 via the cable 203. (Regarding Operation and Operation Control of Ink Application Device) A procedure for applying phosphor ink using such an apparatus configuration will be described. First, the rear glass substrate 21 is placed on the substrate mounting table 103.
It is placed on top and is fixed by suction by operating the suction pump 141.

Next, the ink application device 50 of the first embodiment.
In the same manner as described above, the image pickup unit 120 is scanned and an image is taken over the entire surface of the rear glass substrate 21, and the controller 200 sets the image on the substrate mounting table 103 based on the image data from the image pickup unit 120. Image data in which coordinates and brightness are associated is obtained, and a scanning line is set in the groove between the partition walls.

Next, by driving the elevating mechanism 114 to adjust the height of the nozzle head 112, the nozzle 11
The distance between the lower end of the partition 3 and the upper surface of the partition wall 30 is adjusted. And
The pressure pump 152 is driven to drive the nozzle head unit 1
The phosphor ink is discharged from 10. Then, while maintaining the state of ejecting the ink, the nozzle head unit 110 is scanned to apply the phosphor ink as follows.

FIG. 15 is a diagram showing how the nozzle head 112 scans the rear glass substrate 21. Here, a case where one color (blue) phosphor ink is applied to every two grooves 32a will be described. In the nozzle head 112, three nozzles 113a, 113b, 113c are arranged in a straight line at a distance A, and the nozzle interval A is 2
It is set slightly larger than the pitch of the alternate groove 32a,
It is assumed that the position of the central nozzle 113b and the center of rotation of the nozzle head 112 coincide.

In this figure, the thick arrow (R1 → R2 → R3
→ R4 →) indicates a line in which the center of the nozzle head 112 is scanned. As shown in the figure, the nozzle 113a
The nozzle head 112 is tilted with respect to the Y-axis so that 113b and 113c are positioned on every other groove 32a, and scanning is performed in the X-axis direction (R1 → R2). Next, the nozzle head 112 is shifted in the Y-axis direction by nine partition wall pitches (R2 → R3), and similarly, the nozzle head 112 is tilted with respect to the Y-axis and scanned in the X-axis direction ( R3 → R
Four).

Thereafter, by repeating the same scanning, the fluorescent ink is applied to each groove 32a over the entire rear glass substrate 21, but during this period, the fluorescent ink is continuously applied without stopping the pressurizing pump 152. Discharge. Thereby, the nozzles 113a, 113b, 1
The phosphor ink is prevented from adhering to the lower surface of 13c to make the jet flow unstable.

Further, during the time when the nozzle head 112 is scanned in the X direction, the area between the end of the partition wall 30 and the edge of the substrate mounting table 103 (the area indicated by W1 and W2 in the drawing) is changed to the nozzle head. During the passage of 112, the jet shield mechanism 116 is operated to block the ink jet with the shield tray 117. As a result, it is possible to prevent the phosphor ink from adhering to the vicinity of the end portion of the partition wall 30 (the area indicated by W3 and W4 in the figure) on the rear glass substrate 21.

When the viscosity of the phosphor ink is low, the groove 3
The phosphor ink applied to 2a is near the edge of the partition wall 30 (W
3 and W4 area), the ink that has adhered to the adjacent groove 3
There is a possibility that the particles may flow into the 2b or the groove 32c and cause color mixing, but by preventing the adhesion as described above, this color mixing can be prevented. In addition, this jet shielding mechanism 1
In 16, the shielding tray 117 needs to be inserted between the lower end of the nozzle 113 and the upper surface of the partition wall 30. Therefore, it is conceivable to design the shielding tray 117 to be thin, but the thickness of the shielding tray 117 is ensured so that the phosphor ink can be stored to some extent, and the elevating mechanism 114 is adjusted according to the timing of operating the jet shielding mechanism 116. It is preferable to drive the nozzle head 112 to move it upward.

Further, when the ink is continuously circulated and applied, not only the amount of ink in the container is decreased but also the physical property values are likely to change due to evaporation of the solvent. Therefore, it is preferable to take measures so that the physical properties of the phosphor ink do not exceed the allowable range. For example, the viscosity of the ink can be kept constant by detecting the viscosity in the recovery container 151 and providing a solvent replenishing mechanism for automatically replenishing the fluorescent ink with a solvent or the like. As a result, stable coating can be performed for a long time.

Further, the ink received by the jet shield mechanism often has different physical property values from the ink received by a simple collection container. Therefore, the ink received by the jet shield mechanism is different from the circulating ink. It is preferable to store it in the second recovery container 118 and reuse it separately. [Regarding Position Control of Nozzle Head 112] Also in this embodiment, when the nozzle head 112 is scanned in the X-axis direction, scanning is performed while adjusting in the Y-axis direction as in the first embodiment. Then, by further rotating the nozzle head 112 by the rotation driving mechanism 115, scanning is performed while adjusting the nozzle pitch of the nozzle head 112 in the Y-axis direction.

That is, the three nozzles 113a, 113b,
Nozzle 113a and nozzle 113 at both ends in 113c
Scanning is performed in the X-axis direction while adjusting the position and the rotation angle of the nozzle head 112 in the Y-axis direction so that the c's follow the lines set at the centers of the corresponding grooves 32a. By performing scanning while controlling in this way, even if the grooves 32a, 32b, 32c are curved or the pitch between the partition walls is changed, the plurality of nozzles 113a, 113b, 11 in the nozzle head 112 are
3c can be scanned along the scanning line set at the center of each corresponding groove 32a. Hereinafter, this control will be described more specifically.

FIG. 16 is a partially enlarged view of the image data in which the coordinates on the substrate mounting table 103 are associated with the brightness, and shows the case where the grooves 32a, 32b, 32c are curved in the X axis. . On this image data, as described with reference to FIG. 5 of the first embodiment, the nozzle scanning lines S1, S2, S3.
... is set. And, as shown in the figure, the length is 2A.
Further, the line segments K1, K2, K3 ... Having both ends on the nozzle scanning line S1 and the nozzle scanning line S7 are set at substantially equal pitches.

Then, for each line segment K1, K2, K3 ..., The positions (X, Y coordinates) and X of the midpoints M1, M2, M3 ...
The angles θ1, θ2, θ3 ... With respect to the axes are calculated. The line connecting the midpoints M1, M2, M3 ...
Scan line of the nozzle head 112 (head scan line)
And As can be seen from FIG. 16, this head scanning line is almost the same as the nozzle scanning line S4, although there is a slight deviation.

When the nozzle head 112 is scanned, the center of rotation of the nozzle head 112 (nozzle 113b) is moved while scanning the nozzle head 112 in the X-axis direction, and the head scanning line (middle points M1, M2, M3) is moved. Of the nozzle head unit 110 such that
Drive control of the shaft drive mechanism. At the same time, the center of rotation of the nozzle head 112 is adjusted to the midpoint M1, M2, M3 calculated above.
When it is in the position, the drive of the rotary drive mechanism 115 is controlled so that the angle θ of the nozzle head 112 with respect to the x-axis matches the above calculated angles θ1, θ2, θ3.

By controlling the Y-axis direction and the rotation angle θ in this way during the scanning of the nozzle head 112, the nozzles 113a and 113c at both ends are scanned by the scanning line S.
1, S7 is to be scanned, and the central nozzle 113
a is scanned on the head scanning line (that is, in the vicinity of the nozzle scanning line S4). Therefore, each nozzle 11
3a, 113b, 113c are always scanned near the center of each groove 32a.

[Effects of Providing Mechanism for Collecting Phosphor Ink] When the nozzle is off the groove of the substrate, that is, when the substrate is in the standby position as shown in FIG. Since the generated ink jet is collected in the collection container 151, there is almost no loss even if the phosphor ink is continuously discharged.

Therefore, for example, if the ink is continuously discharged while the rear glass substrate 21 on the substrate mounting table 103 is exchanged, it is possible to stably apply the ink to a plurality of substrates 21 and the fluorescent light is emitted. Less loss of body ink. Further, basically, the discharge of the phosphor ink from the nozzle may be stopped only during the maintenance, and the discharge may be continuously performed thereafter. Alternatively, continuous operation can be performed on a weekly or monthly basis in some cases.

As described above, the coating method of the present embodiment is an excellent method suitable for mass production because the loss of the phosphor ink is small and the groove between the partition walls can be uniformly and stably coated. The coating method of the embodiment can also reduce the manufacturing cost. [Regarding Modifications According to this Embodiment] In consideration of adaptability when changing the operation procedure, the nozzle head unit 110 and the imaging unit 120 are independent of each other on the arm 104 as in the device shown in FIG. Although it is desirable that the nozzle head unit 110 and the image pickup unit 120 are integrated, the same operation as above is possible.

Further, in the present embodiment, as a method for preventing the color mixture of the phosphor ink at the partition wall end portion of the rear glass substrate 21, the method of blocking the ink jet is shown. For example, as shown in FIG. , Back glass substrate 2
If the auxiliary partition wall 33 is formed along the end of the partition wall 30 on the first partition 1, the grooves 32a, 32b, 3 are formed at the end portion of the partition wall 30.
Since 2c is closed, even if the phosphor ink applied to the groove 32a adheres to the vicinity of the partition wall end portion on the rear glass substrate 21, it does not flow into the adjacent grooves 32b and 32c, so that color mixing can be prevented.

[Third Embodiment] The ink applying apparatus of the present embodiment is the same as the ink applying apparatus of the second embodiment, but the circulation mechanism for circulating the phosphor ink is further devised. FIG. 18 is a diagram showing the configuration of the phosphor ink circulation mechanism in the ink application device of this embodiment.

This circulation mechanism 160 is similar to the circulation mechanism 150 of the second embodiment, in that the nozzle 1 of the nozzle head 112 is
The phosphor ink ejected from the nozzle 13 is collected by the collecting container 151, and the collected phosphor ink is collected again by the nozzle head 1.
Although it is to be sent to 12 for circulation, a collection container 151
A disperser 161 for redispersing the phosphor ink is inserted in a pipe path from the nozzle head 112 to the nozzle head 112.

The dispersing device 161 is a flow tube type sand mill having zirconia beads having a particle diameter of 2 mm or less filled therein, and the rotating disk 163 is rotated in a certain direction at a rotation speed of 500 rpm or less, whereby The phosphor ink that flows through is stirred and dispersed together with the beads. In addition to this, the circulation mechanism 160 has a collection container 151.
The circulation pump 164 that feeds the inside of the fluorescent substance ink to the dispersing device 161, the server 165 that stores the fluorescent substance ink that has passed through the dispersing device 161, and the nozzle head 11 from the server 165
Pressurizing pump 166 that pressurizes and supplies phosphor ink to 2
Is provided.

As a result, the phosphor ink collected in the collecting container 151 is redispersed by the disperser 161, and then ejected again from the nozzle head 112. The disperser 1
Besides 61, an attritor, a jet mill, or the like can also be used as 61. If the phosphor ink is manufactured and then left for a long time, the dispersion state of the phosphor ink may deteriorate. Further, when the phosphor ink is circulated by the circulation mechanism as in the second embodiment, the dispersed state of the phosphor ink may be deteriorated or secondary aggregates may be generated. Therefore, the nozzle may be clogged or the applied state of the applied phosphor ink to the groove 32 may be reduced, but in the circulation mechanism 160 of the present embodiment, since the phosphor ink is redispersed immediately before being discharged, Problems are resolved.

The effect of such redispersion of the phosphor ink is not limited to the case of redispersing the phosphor ink in the ink circulation mechanism, but generally, from the time the phosphor ink is manufactured to the time it is applied. It can also be applied when setting conditions.
Here, preferable conditions from the production of the phosphor ink to the coating thereof will be described. FIG. 19 is a diagram showing steps from the production of the phosphor ink to the coating thereof.

When the phosphor ink is manufactured, the phosphor powder of each color which is the raw material of the phosphor ink, the resin and the solvent are mixed and dispersed (primary dispersion). In this primary dispersion step, when dispersing with a disperser using a dispersion medium (media) such as a sand mill, a ball mill, or a bead mill, zirconia beads having a particle diameter of 1.0 mm or less are used as a medium and the bead mill is used within a short time of 3 hours. It is preferable to carry out dispersion. This is for suppressing the damage to the phosphor powder and suppressing the contamination (contamination) of impurities.

The viscosity of the phosphor ink is 15 to 20.
It is desirable to adjust to about 0 cp so that there are no large agglomerates larger than about 1/2 of the nozzle diameter. If the phosphor ink produced in this way is set in an ink application device immediately after production and applied, the good dispersion state obtained by primary dispersion is maintained even during application, so that re-dispersion is not necessary. Can be uniformly applied to each groove, and a good application condition is relatively good. Then, in order to set the ink on the ink application device immediately after production, the dispersion device for the phosphor ink and the ink application device are set in the same workplace, and the produced phosphor ink is directly set on the ink application device. It is thought to be good to apply.

In terms of time, it is preferable to apply within a few hours, preferably within an hour, after producing the phosphor ink. On the other hand, when the phosphor ink is manufactured and set in the ink applicator after a long time and then applied, it is applied after a long time has passed after the primary dispersion, so that the dispersion state may decrease during that time. Secondary aggregates are easily formed. Therefore, if this is applied directly from the nozzle, it is difficult to apply it uniformly to each groove, and the nozzle is likely to be clogged.

However, even if the phosphor ink has been used for a long time after the manufacture (primary dispersion), if the phosphor ink is redispersed in the secondary dispersion step and then set and applied in the ink application device, a good dispersion state is obtained. Since it can be applied by, it can be applied uniformly to each groove, and it is possible to avoid clogging of the nozzle. In the secondary dispersion, a large shear force is not necessary because the main purpose is to disperse the secondary aggregates. Rather, stirring with a weak force causes less damage to the phosphor.

Therefore, it is effective to use zirconia beads having a particle diameter of 2 mm or less and to re-disperse them at a rotation speed of 500 rpm or less within 6 hours. The reason why zirconia beads are used is to avoid contamination as in the case of primary dispersion. With respect to the phosphor ink adjusted by the secondary dispersion as described above, the viscosity is set to about 15 to 200 cps in order to obtain stable ejection from the nozzle, and large agglomerates of about ½ or more of the nozzle diameter are generated. It is desirable not to.

[Modifications of First to Third Embodiments] In the above embodiments, an example in which the phosphor ink is directly applied to the grooves between the partition walls has been shown. However, the reflector ink is applied to the grooves between the partition walls. Then, it can also be applied to the case where a phosphor layer is formed thereon. That is, the reflection layer and the phosphor layer 31 are formed by applying the reflection material ink and the phosphor ink using the above-mentioned ink application device.

The reflection material ink is a mixture of a reflection material, a binder and a solvent component. As the reflection material, a white powder having a high reflectance such as titanium oxide or alumina can be used. Titanium oxide having an average particle size of 5 μm or less is good. In the above embodiment, the AC type PDP has been described as an example, but the present invention is not limited to the AC type PDP, and the PDP in which the barrier ribs are arranged in stripes and the phosphor layer is disposed between the barrier ribs. It can be widely applied to make

[0141]

[Example 1] Based on the first embodiment, a phosphor ink is prepared by changing the kinds and amounts of phosphor particles, resin and solvent, and the prepared phosphor ink is applied to the PDP.
Was produced.

[0142]

[Table 1]

[0143]

[Table 2]

[0144]

[Table 3]

[0145]

[Table 4]

Nos. In Tables 1, 2 and 3 Nos. 1 to 9 relate to the examples, and phosphor inks were prepared by dispersing with a sand mill using zirconia balls of 0.2 mm to 2 mm. Particle size of phosphor, kind and amount of resin, kind and amount of solvent, kind and amount of surfactant, dispersant, viscosity at the time of applying phosphor ink (shear rate at 25 ° C is 100 s
Viscosity at ec ⁻¹ ) and the like are as shown in Tables 1 to 3.

In manufacturing the PDP of the embodiment, the pitch of the partition walls 30 on the rear glass substrate 21 is 0.15 mm.
In addition, the height was set to 0.15 mm. The phosphor layer was formed by applying each color phosphor ink so as to fill the upper part of each groove, and then firing at 500 ° C. for 10 minutes. The discharge gas to be filled is neon (Ne) gas containing 10% xenon (Xe) gas, and the filling pressure is 500T.
orr.

On the other hand, the sample No. Nos. 10 to 12 relate to comparative examples, and in producing the phosphor ink, in the sample No. 10, the acrylic resin and the dispersant (glyceryl trioleate) were combined in combination, and the sample No.
In No. 11, ethyl cellulose having an ethoxy group content of 50% was combined with terpineol, but no dispersant was added. In addition, the sample No. In No. 12, polyvinyl alcohol and water are combined, but no dispersant is contained. Other than that, the sample No. of the example. A PDP of a comparative example was manufactured by setting in the same manner as 1-9.

Comparative test: Then, with respect to each of the manufactured PDPs, the adhered state of the phosphor on the side wall of the partition wall, the presence or absence of color mixture,
The panel brightness was measured. For the presence or absence of color mixing, see PDP
Was evaluated for each color and the luminescent color was measured.

As a result, the PD of any of the Examples and Comparative Examples
Also in P, the phosphor adhered to the upper part of the side wall of the partition wall, and no color mixture was observed. Regarding panel brightness, PDP discharge sustain voltage 150V frequency 30KHz
It was driven by and measured with a panel luminance meter. The results are shown in Table 1.
~ 4. When the wavelength of ultraviolet rays generated when driving these PDPs was also examined, the excitation wavelength due to the Xe molecular beam centered at 173 nm was observed.

Regarding each of the prepared phosphor inks,
An experiment of continuously ejecting from a nozzle for a long time was also conducted. As a result, the phosphor inks of the examples were able to be continuously ejected for 100 hours, but the phosphor inks of the comparative examples caused nozzle clogging within 8 hours. Consideration: As shown in Tables 1 to 4, regarding the luminance, the panel luminance of the example (No. 1 to 9) is 530 cd / m ² or more, and the panel luminance of the comparative example (No. 10 to 12) ( It is superior to 460 to 480 cd / m ² ). This is because the PDP of the embodiment is more
It is considered that this is because the ratio of the phosphor layer attached to the side surface of the partition wall to the bottom surface of the groove is large. [Example 2] In this example (Sample Nos. 21 and 22),
Red _{(Y, Gd) BO 3:} Eu, blue BaMgAl ₁₀ O _17:
A phosphor ink in which negatively charged oxide (SiO ₂ ) particles are adhered (coated) on the surface of each color phosphor particle of Eu and green ZnSiO ₄ : Mn is used.

[0152]

[Table 5]

The method of attaching the SiO ₂ particles to the surface of the phosphor particles is as follows. First, a suspension of phosphors of each color and a suspension of SiO ₂ particles (the particle diameter is 1/10 or less of the phosphor particles). Was prepared, and both the prepared suspensions were mixed and stirred, suction filtered, dried at 125 ° C. or higher, and then calcined at 350 ° C. In this way, phosphor particles having SiO ₂ particles attached thereto and a resin component made of ethyl cellulose,
Mixed solvent of terpineol and pentanediol (1 /
1) were mixed in the proportions shown in Table 5 and mixed and dispersed by a jet mill to prepare a phosphor ink. When mixed and dispersed,
The pressure applied to the mixed solution is 10 Kgf / cm ^{2 to} 200 K
It was adjusted to the range of gf / cm ² .

The phosphor ink thus prepared is shown in Table 5.
A PDP was prepared in the same manner as in Example 1 except that the viscosity was adjusted and the coating was performed. With respect to the manufactured PDP, the adhered state of the phosphor on the side wall of the partition wall, the presence or absence of color mixture, and the panel brightness were measured in the same manner as in Example 1 above. As a result, in all cases, the phosphor adhered to the upper part of the partition walls, and no color mixture occurred.

The panel brightness was good as shown in Table 5. In addition, the sample No. No nozzle clogging occurred in any of the phosphor inks 21 and 22 even when continuously applied for 100 hours or more.

[0156]

Example 3 In this example, an example of adding various surfactants as a dispersant and a charge eliminating substance (Sample Nos. 31 to 37) and conductive fine particles as a charge eliminating substance are added to the phosphor ink. Examples (Sample Nos. 38 to 42) are shown. In addition, among these, the sample No. 31 to 34 are also examples in which oxides such as ZnO and MgO are attached to the surface of the phosphor.

Sample No. Reference numeral 43 is an example in which no static elimination material was added.

[0158]

[Table 6]

[0159]

[Table 7]

[0160]

[Table 8]

[0161]

[Table 9]

Regarding the type and particle size and amount of the phosphor of the phosphor ink used in each example, the type and amount of the oxidizing agent attached to the phosphor, the type and amount of the resin, the type and amount of the solvent, etc., As shown in Tables 6 and 7. In addition, the types and amounts of surfactants and static eliminators, the viscosity of the phosphor ink when applied (25
Viscosity at a shear rate of 100 sec ^-1 at 0 ° C) is shown in Tables 8 and 9. Then, using a nozzle having a nozzle diameter of 50 μm, the phosphor ink is ejected to apply the phosphor ink while scanning while keeping the distance between the tip of the nozzle and the rear glass substrate at 1 mm, and under the same conditions as in Example 1. A PDP was produced.

In this example, in order to improve the wettability of the phosphor ink application surface, the surface of the rear glass substrate with the partition wall was adjusted with an excimer lamp (center wavelength 172 nm) by 10 before applying the phosphor ink. Irradiate for 1 second to 1 minute,
Even after firing the phosphor layer, the surface of the rear glass substrate on which the phosphor layer is formed is removed by excimer lamp (center wavelength 172n) in order to remove binder and residue remaining in the phosphor layer.
m) for 10 seconds to 1 minute.

For each manufactured PDP, the panel brightness when it was driven and the presence or absence of streak unevenness were also measured. Regarding panel brightness, the discharge sustaining voltage of the PDP is 15
It was driven at 0 V frequency of 30 KHz and measured by a panel luminance meter. Regarding streaks, the entire PDP screen was displayed in white and the presence or absence of streaks was visually observed.

When the wavelength of ultraviolet rays generated when these PDPs were driven was also examined, the excitation wavelength due to the Xe molecular beam centered at 173 nm was observed. The results are shown in Tables 8 and 9. As shown in Tables 8 and 9, the sample No. 31 to 42 are
Sample No. High brightness is obtained as compared with the brightness of 43. In addition, the sample No. In No. 43, streaks were generated, whereas in Sample No. 43. In Nos. 31 to 42, there was no streaking.

Further, when the phosphor layer was observed for each of the manufactured PDPs, no color mixture of the phosphor was observed, but regarding the shape of the phosphor layer, the sample No. 43
Sample No. In Nos. 31 to 42, the adhesion of the phosphor to the side surface of the partition wall was better. Consideration: The test results for such brightness and streak unevenness are shown in Sample No. 1 in which a discharging substance is added to the phosphor ink. 31
Nos. 42 to 42 are samples No. in which the discharging substance is not added to the phosphor ink. It is considered that it was caused by the fact that the phosphor ink was applied uniformly on the side surface of the partition wall and the bottom surface of the groove in a well-balanced manner than in No. 43.

[0167]

[Example 4] [Example relating to primary dispersion] Embodiment 3
As shown in Table 10, each color phosphor ink was manufactured by variously changing the dispersion method (bead type, particle size, and dispersion time) at the time of ink production (primary dispersion), as shown in Table 10.

[0168]

[Table 10]

In each phosphor ink, 60 wt% of each color phosphor powder having an average particle diameter of 3 μm and 1 wt of ethyl cellulose are used.
%, And a mixed solvent of terpineol and limonene was used as a solvent. Then, the manufactured phosphor ink was evaluated for brightness, particle size of phosphor powder (measurement of phosphor particle size after primary dispersion), and evaluation of the presence or absence of aggregates.

In the evaluation of brightness, the phosphor ink after dispersion was baked at 500 ° C. in the atmosphere to form a phosphor layer, which was placed in a vacuum chamber and irradiated with vacuum ultraviolet light by an excimer lamp. Excitation light emission sometimes generated was measured with a luminance meter. The evaluation results are shown in Table 10. From the evaluation results in Table 10, it can be seen that, for each of the colors red, green, and blue, when glass beads are used as the dispersion medium, the brightness is lower than when zirconia beads are used. In addition, when glass beads are used as the dispersion medium, many components of sodium (Na), calcium (Ca), and silicon (Si) are detected.

As described above, the brightness is lower when glass beads are used as the dispersion medium, because the glass component is subjected to a strong impact when a shearing force is applied at the time of dispersion, so that the glass component is contaminated with impurities (contamination). It is thought that this is because it mixes into the ink as), and this becomes a luminescence killer. Further, from the evaluation results of Table 10, it is understood that even if the type of the dispersion medium used is the same, the brightness changes if the particle size or the dispersion time changes. This is probably because even if the same shearing force is applied, the collision coefficient differs when the particle diameter of the dispersion medium is different, and the number of collisions with the phosphor powder is different when the dispersion time is different.

From the results shown in Table 10, the particle size of the phosphor after dispersion is smaller than that before dispersion. From this, it can be seen that the phosphor powder is crushed by dispersion and the interface state is deteriorated. [Examples Related to Secondary Dispersion] Next, the produced phosphor inks of respective colors were temporarily dispersed, allowed to stand for 72 hours, and then subjected to secondary dispersion. In this secondary dispersion, as shown in Table 11, the particle size of the zirconia beads as a dispersion medium and the dispersion time were variously changed.

[0173]

[Table 11]

With respect to each phosphor ink after the secondary dispersion, the brightness was evaluated, the particle size of the phosphor powder was measured (the particle size of the phosphor after the primary dispersion was measured), and the presence or absence of aggregates was evaluated. The evaluation results are shown in Table 11. As is clear from Table 11, when the dispersion time in the secondary dispersion is less than 1 hour, aggregates remain in the phosphor ink for each color of red, green, and blue. Has disappeared. Further, even when the dispersion time is extended, the particle size of the phosphor particles does not change.

From this, it is understood that the secondary dispersion using zirconia in the dispersion medium can disperse the aggregates without crushing the phosphor particles themselves. Further, it can be seen from Table 11 that no decrease in brightness is observed even if the dispersion time is extended. From this, it can be seen that the secondary dispersion using zirconia as the dispersion medium enables dispersion with less damage to the phosphor surface.

[0176]

As described above, according to the present invention,
While applying the phosphor ink continuously from the nozzles, when the phosphor ink is applied by relatively scanning along the groove between the partition walls arranged on the plate, based on the positional information on each groove By adjusting the position of the nozzle through which the nozzle passes, even if the groove is curved, the nozzle can scan so that it always passes through the center of the groove. It is possible to uniformly apply the phosphor ink and attach it in a well-balanced manner to the bottoms of the grooves and the side surfaces of the partition walls.

When the phosphor ink is applied by continuously scanning the phosphor ink from the nozzles and relatively scanning along the grooves between the partition walls arranged on the plate. The width was measured over the longitudinal direction of the groove, and the phosphor ink was ejected from the nozzle while adjusting the amount of the phosphor ink applied per partition wall length according to the measured groove width. As a result, the phosphor ink can be uniformly applied even when the groove width varies or the width varies in the groove.

Further, when the phosphor ink is sequentially applied to the plurality of grooves, the phosphor ink should be applied while maintaining the state of continuously ejecting the phosphor ink from the nozzle even when the nozzle is off the groove. Since it is possible to prevent the adhesion of the phosphor ink near the nozzle outlet, it is possible to obtain a stable ink jet flow.
The phosphor ink can be uniformly applied to the plurality of grooves.

Further, by dispersing the ink again with a disperser before continuously discharging the phosphor ink from the nozzle, the dispersibility of the applied phosphor ink is improved. It can be attached in a well-balanced manner to the bottom of each groove and the side surface of the partition wall. Further, in the phosphor ink used for manufacturing the PDP, the average particle size is 0.5 to 5
μm phosphor powder, OH group-terminated solvent such as terpineol, butyl carbitol acetate, butyl carbitol, pentanediol, limonene are used as a binder, and ethoxy group (-OC) in the cellulose molecule is used as a binder. ₂ H ₅ ) content of 49% or more of ethyl cellulose or ethylene oxide-based polymer is used, and by adding a dispersant, the phosphor ink filled in the grooves between the partition walls is also well formed on the side surfaces of the partition walls. It is possible to attach the phosphor ink to the bottom of each groove and the side surface of the partition wall in good balance.

In addition, in such a phosphor ink,
PDP with a fine structure by adding a static eliminator
Even in this case, the phosphor ink can be uniformly applied to the grooves between the partition walls, and even when the completed PDP is driven, streak unevenness hardly occurs.

[Brief description of drawings]

FIG. 1 is a perspective view showing an AC surface discharge type PDP according to an embodiment.

FIG. 2 is a configuration diagram of a display device in which a circuit block is mounted on the PDP.

FIG. 3 is a schematic configuration diagram of an ink application device according to the first embodiment.

FIG. 4 is a diagram schematically showing image data obtained by groove position detection of the ink application device according to the first embodiment.

5 is a partially enlarged view of FIG. 4 and a graph schematically showing the luminance at each position on the search line L1.

6 is an example of a partially enlarged view of FIG.

FIG. 7 is a diagram showing a coating state and a state of a formed phosphor layer when a nozzle is displaced from a central portion of a groove.

FIG. 8 is a diagram schematically showing how a phosphor layer is formed after applying a phosphor ink to a groove.

FIG. 9 is a diagram schematically showing the relationship between the concentration of the resin binder in the phosphor ink and the shape of the phosphor layer formed.

FIG. 10 is a graph comparing viscosities of a phosphor ink according to the present invention and an ink used for conventional screen printing or the like.

FIG. 11 is a diagram showing a discharge state of phosphor ink from a nozzle.

FIG. 12 is a perspective view showing an ink application device according to a second embodiment.

FIG. 13 is a front view (partial cross section) of the ink application device.

14 is an enlarged view of the nozzle head unit shown in FIG.

FIG. 15 is a diagram showing a manner in which a nozzle head scans a rear glass substrate in the ink application device.

FIG. 16 is an example of a partially enlarged view of image data obtained by detecting the groove position of the ink application device.

FIG. 17 is a diagram showing a modification of the second embodiment.

FIG. 18 is a diagram showing a configuration of a phosphor ink circulation mechanism in the ink application device according to the third embodiment.

FIG. 19 is a diagram showing steps from the production of phosphor ink to the coating thereof.

[Explanation of symbols]

10 Front panel 20 back panel 21 Rear glass substrate 30 bulkheads 31 phosphor layer 32 grooves 33 Auxiliary bulkhead 50 ink applicator 51 ink server 52 Pressurizing pump 53 nozzle head 54 nozzles 55 Groove detection head 56 Substrate mounting table 100 device body 101 body base 103 substrate mounting table 110 nozzle head unit 112 nozzle head 112a rotating shaft 113 nozzles 115 rotation drive mechanism 116 Jet shielding mechanism 120 imaging unit 150 circulation mechanism 151 collection container 152 Pressurizing pump 154 Ink replenisher 160 Circulation mechanism 161 Disperser 164 Circulation pump

─────────────────────────────────────────────────── ─── Continuation of front page (31) Priority claim number Japanese Patent Application No. 10-287645 (32) Priority date October 9, 1998 (Oct. 9, 1998) (33) Country of priority claim Japan (JP) (31) Priority claim number Japanese Patent Application No. 11-17855 (32) Priority date January 27, 1999 (January 27, 1999) (33) Country of priority claim Japan (JP) (31) Priority claim number Japanese Patent Application No. 11-88717 (32) Priority Date March 30, 1999 (March 30, 1999) (33) Priority claiming country Japan (JP) (72) Inventor Kanako Miyashita 1006 Kadoma, Kadoma, Osaka Prefecture Address Matsushita Electric Industrial Co., Ltd. (72) Inventor Keisuke Sumita 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Nobuyuki Kirihara 1006, Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. In-company (56) References JP-A-10-334805 (JP, A) (58) (Int.Cl. ^7, DB name) H01J 9/227 H01J 11/02 H01J 9/02

Claims (9)

(57) [Claims] 1. A plate having a plurality of partition walls is provided with a phosphor ink applying step of applying a phosphor ink to a groove between the partition walls, wherein the phosphor ink applying step comprises anions. Surfactant
And relatively discharging the nozzle along the groove between the partition walls while ejecting the phosphor ink to which the static eliminator other than the nonionic surfactant is added so as to form a continuous flow from the nozzle. A method of manufacturing a plasma display panel, characterized in that the plasma display panel is applied by. 2. A static eliminator added to the phosphor ink used in the phosphor layer forming step, comprising a baking step of baking the phosphor ink applied to the first plate after the phosphor ink applying step. The method of manufacturing a plasma display panel according to claim 1, wherein the material has a property of being lost in the firing step or a property of losing conductivity. Wherein the neutralizing substance is added to the phosphor ink used in the phosphor layer formation step, according to claim 1, characterized in that it consists of one selected from a surfactant and conductive particles Manufacturing method of plasma display panel. 4. The method of manufacturing a plasma display panel according to claim 3, wherein the conductive fine particles are made of a material selected from carbon, graphite, metals and metal oxides. 5. A phosphor ink, which is used to form a phosphor layer of a plasma display panel and is ejected from a nozzle that scans along a partition of a plate in which the partition is arranged in a stripe pattern, the phosphor ink comprising: Particles, Binders, Solvents, Anionic and Nonionic Surfactants
A phosphor ink characterized by being mixed with a charge-eliminating substance other than . Wherein said neutralizing agent is during the firing for forming the phosphor layer, claim 5, characterized in that has a property that the nature or the conductive that is lost from the phosphor layer is lost The described phosphor ink. 7. The phosphor ink according to claim 5 , wherein the charge eliminating material is selected from a surfactant and conductive fine particles. 8. The phosphor ink according to claim 7, wherein the conductive fine particles are made of a material selected from carbon, graphite, metals and metal oxides. 9. The phosphor ink is produced by dispersing phosphor particles, a binder, a solvent, and a charge-eliminating substance in a disperser, and has a shear rate of 100 at 25 ° C.
The phosphor ink according to any one of claims 5 to 8, wherein the viscosity at sec ^-1 is 10 to 1000 centipoise.