JP4759882B2 - Method for manufacturing plasma display panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma display panel (PDP) using gas discharge luminescence used for a color television receiver or display for displaying characters or images, and a method for manufacturing the same.
[0002]
[Prior art]
Hereinafter, a conventional plasma display panel will be described with reference to the drawings. FIG. 5 is a cross-sectional view schematically showing an AC type (AC type) plasma display panel.
[0003]
In FIG. 5, reference numeral 41 denotes a front glass substrate, and display electrodes 42 are formed on the front glass substrate 41. Further, the display electrode 42 is covered with a dielectric glass layer 43 and a magnesium oxide (MgO) dielectric protective layer 44.
[0004]
Reference numeral 45 denotes a rear glass substrate. On the rear glass substrate 45, an address electrode 46, a partition wall 47, and a phosphor layer (50 to 52) are provided. A discharge space 49 encloses a discharge gas. It has become. The phosphor layers are arranged in order of three color layers of red 50, green 51, and blue 52 for color display. Each of the phosphor layers (50 to 52) emits light by excitation with vacuum ultraviolet rays (wavelength 147 nm) having a short wavelength generated by discharge.
[0005]
As the phosphor constituting the phosphor layers 50 to 52, the following materials are generally used.
[0006]
“Blue phosphor”: BaMgAl ₁₀ O ₁₇ : Eu
“Green phosphor”: Zn ₂ SiO ₄ : Mn or BaAl ₁₂ O ₁₉ : Mn
“Red phosphor”: Y ₂ O ₃ : Eu or (YxGd1-x) BO ₃ : Eu
Each color phosphor can be produced as follows.
[0007]
In the blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu), first, barium carbonate (BaCO ₃ ), magnesium carbonate (MgCO ₃ ), and aluminum oxide (α-Al ₂ O ₃ ) are paired in an atomic ratio of Ba, Mg, and Al. Mix to make 10: 1. Next, a predetermined amount of europium oxide (Eu ₂ O ₃ ) is added to the mixture.
[0008]
Then, it is mixed with an appropriate amount of flux (AlF ₂ , BaCl ₂ ) by a ball mill, and fired at 1400 ° C. to 1650 ° C. for a predetermined time (for example, 0.5 hour) in a reducing atmosphere (in H ₂ and N ₂ ). .
[0009]
The red phosphor (Y ₂ O ₃ : Eu) is blended so that the atomic ratio of yttrium hydroxide Y ₂ (OH) ₃ , boric acid (H ₃ BO ₃ ) and Y, B is 1: 1 as a raw material. Next, a predetermined amount of europium oxide (Eu ₂ O ₃ ) is added to this mixture, mixed with a suitable amount of flux by a ball mill, and fired at 1200 ° C. to 1450 ° C. for a predetermined time (for example, 1 hour). obtain.
[0010]
In the green phosphor (Zn ₂ SiO ₄ : Mn), zinc oxide (ZnO) and silicon oxide (SiO ₂ ) are blended as raw materials so that the atomic ratio of Zn and Si is 2: 1. Next, a predetermined amount of manganese oxide (Mn ₂ O ₃ ) is added to the mixture, mixed by a ball mill, and then obtained in air at 1200 ° C. to 1350 ° C. for a predetermined time (for example, 0.5 hour).
[0011]
A phosphor material having a predetermined particle size distribution is obtained by pulverizing the phosphor particles produced by the above production method after pulverization.
[0012]
Hereinafter, a conventional method for manufacturing a PDP will be described.
[0013]
An address electrode made of silver is formed on the back glass substrate, and a visible light reflecting layer made of dielectric glass and a glass partition are formed on the back glass substrate at a predetermined pitch.
[0014]
A phosphor layer is formed by disposing each color phosphor paste including red phosphor, green phosphor, and blue phosphor in each space sandwiched between the partition walls, and the phosphor layer is fluorescent at about 500 ° C. after the formation. The body layer is fired to remove resin components and the like in the paste (phosphor firing process).
[0015]
After firing the phosphor, a low-melting glass paste is applied around the back plate as a sealing material for sealing with the front plate, and calcined at about 350 ° C. to remove the resin component and the like in the low-melting glass paste (low Melting point glass paste calcining step).
[0016]
Thereafter, a front plate on which a display electrode, a dielectric glass layer, and a protective layer are sequentially formed, and the back plate are arranged opposite to each other so that the display electrode and the address electrode are orthogonal to each other through a partition wall, and fired at about 450 ° C. The periphery is sealed with glass (sealing process).
[0017]
Thereafter, the inside of the panel is exhausted while being heated to about 350 ° C. (exhaust process), and a discharge gas is introduced by a predetermined pressure after completion.
[0018]
[Problems to be solved by the invention]
In the conventional method of manufacturing a plasma display panel, there are several steps that require substrate heating as described above.
[0019]
However, there is a problem that the phosphor used is thermally deteriorated in these heating processes, and the blue phosphor is largely deteriorated particularly in the sealing process. It is considered that this is because BaMgAl ₁₀ O ₁₇ : Eu used as a blue phosphor is thermally degraded in the sealing process, causing a decrease in emission intensity and emission chromaticity.
[0020]
In addition, there is a problem that discharge characteristics deteriorate when impurity gases such as H ₂ O and CO ₂ remaining inside the panel before the exhaust process cannot be exhausted sufficiently in the exhaust process.
[0021]
In order to solve this, a dry gas is introduced into the panel at the time of sealing, a sealing method for suppressing blue deterioration (Japanese Patent Application No. 11-168895) and a sealing for reducing impurity gas remaining inside the panel until the exhaust process. An intake / exhaust method has been considered (Japanese Patent Application No. 4-33837).
[0022]
However, in these methods, before the panel is completely sealed, in order to introduce gas into the panel, an air flow is formed in the gap of the sealing material, and that part is sealed to the end. It remained as a hole without causing a sealing error, and the sealing process became unstable.
[0023]
Therefore, in view of such problems, the present invention can seal the panel with a stable process, hardly causes thermal degradation of the phosphor, and reduces impurity gas in the process up to the exhaust process. An object of the present invention is to provide a plasma display panel that operates at a relatively high luminous efficiency, has a high color temperature, and good color reproducibility.
[0024]
[Means for Solving the Problems]
In order to achieve the above object, a method of manufacturing a plasma display panel according to the present invention includes a front plate and a back plate having a phosphor layer formed on at least one and a sealing sealant layer formed on at least one. Sealing is performed by maintaining a sealing temperature equal to or higher than a temperature (softening point) at which the sealing sealing material is softened while flowing a dry gas in the internal space in a state of being overlapped so that an internal space is formed therebetween. In the method of manufacturing a plasma display panel including a sealing step, a dry gas starts to flow into the internal space after the temperature becomes equal to or higher than the softening point of the sealing material.
[0025]
In addition, in the state where the front plate and the back plate, in which the phosphor layer is formed on at least one and the sealing seal material layer is formed on at least one, are overlapped so that an internal space is formed between the two substrates, A sealing step of sealing by keeping the sealing temperature equal to or higher than the temperature at which the sealing sealing material is softened while alternately repeating the operation of filling the internal space with the dry gas and the operation of discharging the gas from the internal space. In the method of manufacturing a plasma display panel, the operation of filling the internal space with a dry gas and the operation of discharging the gas from the internal space are alternately started after the temperature becomes equal to or higher than the softening point of the sealing material. It is characterized by that.
[0026]
In the above-mentioned configuration, it is preferable that when heating to the sealing peak temperature, an operation of flowing or filling a dry gas into the internal space and an operation of discharging the gas from the internal space are alternately started.
[0027]
According to the fourteenth aspect of the present invention, an inner space is formed between a front substrate and a rear substrate in which a phosphor is formed on at least one substrate and a sealing seal member is formed on at least one substrate. In a manufacturing method of a display panel comprising a sealing step of sealing while flowing a cleaning gas in the inner space in a superposed state, in the sealing step, the temperature is lower than a softening point temperature of the sealing seal member The cleaning gas is allowed to flow into the internal space at a temperature, and the flow of the cleaning gas is stopped near the softening point temperature of the sealing seal member.
[0028]
Moreover, it is preferable that after the sealing member is softened and the panel is hermetically sealed, the cleaning gas starts to flow again into the internal space.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment)
Hereinafter, a method for manufacturing a plasma display panel according to an embodiment of the present invention will be described. FIG. 3 is a cross-sectional view schematically showing an AC surface discharge type plasma display panel according to one embodiment of the present invention. Although only one cell is shown in FIG. 3, a PDP is configured by arranging a large number of cells that emit red, green, and blue colors.
[0030]
This PDP has a front plate in which a display electrode 22, a dielectric glass layer 23 and a protective layer (MgO) 24 are arranged on a front glass substrate 21, an address electrode 26, a visible light reflecting layer 27 on a rear glass substrate 25, The barrier plate 28 and the back plate on which the phosphor layer 29 is disposed are bonded together, and a discharge gas is sealed in a discharge space formed between the front plate and the back plate.
[0031]
As the composition of the phosphor material constituting the phosphor layer, those generally used for the phosphor layer of PDP can be used. As a specific example,
“Blue phosphor”: BaMgAl ₁₀ O ₁₇ : Eu
"Green phosphor": Zn ₂ SiO ₄ : Mn
“Red phosphor”: (Y, Gd) BO ₃ : Eu
Can be mentioned.
[0032]
Hereinafter, a sealing process in the present embodiment for removing the influence of impurity gas containing water vapor released from each member (particularly MgO) in a stable process at the time of sealing will be described.
[0033]
(First embodiment of the present invention)
Hereinafter, a method for manufacturing a plasma display panel according to the first embodiment of the present invention will be described.
[0034]
FIG. 1 shows a temperature profile of the sealing process of the present embodiment. Moreover, the panel and apparatus structure which bonded the front board 1 and the back board 2 before sealing are shown in FIG. A sealing material 3 for sealing is provided between the front plate 1 and the back plate 2, and a first glass tube 5 connected to an exhaust device 4 and a dry gas introduction device 6 are connected to the back plate 2. Two glass tubes 7 are formed. The first and second glass tubes are also provided with a sealing material 3 for sealing, and are fixed by a leaf spring (not shown). In the present embodiment, low melting glass is used as a sealing material for sealing.
[0035]
This panel was sealed by heating to a temperature equal to or higher than the softening point temperature of the low-melting-point glass with the temperature profile of FIG.
[0036]
In this sealing step, when the temperature is raised, the panel is heated to a temperature equal to or higher than the softening point of the low-melting-point glass that is a sealing material for sealing, and then the exhaust of the panel is started through the first glass tube, and the second glass tube The introduction of dry gas was started. In this step, the gas released from the front plate 1 and the back plate 2 is replaced with the dry gas. As a result, the water vapor is not confined in a narrow discharge space as in the conventional sealing process, and it is possible to suppress the deterioration of the blue phosphor during sealing, and the residual impurity gas can be reduced. In addition, heating to a temperature above the softening point of the low-melting glass, the panel is completely sealed, and after the glass tube is completely bonded, the dry gas is allowed to flow through the panel, so that sealing is performed stably. It was.
[0037]
(Second embodiment of the present invention)
Hereinafter, a method for manufacturing a plasma display panel according to the second embodiment of the present invention will be described.
[0038]
FIG. 6 shows a temperature profile in the sealing step of the present embodiment. Further, FIG. 7 shows a panel and device configuration in which the front plate 1 and the back plate 2 before sealing are bonded together. A sealing material 3 for sealing is provided between the front plate 1 and the back plate 2, and a glass tube 7 connected to the dry gas introduction device 6 through a valve 9 is formed on the back plate 2. The glass tube 7 is also provided with a sealing material 3 for sealing, and is fixed by a leaf spring (not shown). In the present embodiment, low melting glass is used as a sealing material for sealing.
[0039]
This panel was sealed by heating to a temperature equal to or higher than the softening point temperature of the low-melting glass with the heating furnace 8 in the temperature profile of FIG.
[0040]
In this sealing step, the valve 9 is opened, and the dry gas is introduced into the panel through the glass tube 7 when the panel is heated by the dry gas introduction device 6. Below the softening point temperature of the sealing member 3 for sealing, since the sealing member 3 for sealing is not softened, there are many gaps between the substrate and the gas introduced from the gap and the substrate into the panel. The released impurity gas is discharged.
[0041]
However, if the introduction of the dry gas is continued, a gas flow is formed in the gap between the sealing material 3 for sealing, and the portion remains as a hole without being sealed until the end, causing a sealing error. The landing process becomes unstable. For this reason, the valve 9 is closed near the softening point temperature of the sealing material 3 for sealing, and the introduction of the dry gas is stopped.
[0042]
Since the gas is released from the substrate even below the softening point temperature of the sealing member 3 for sealing, the effect of exhausting the released gas from the substrate below the softening point temperature to the outside of the panel by flowing a dry gas between the substrates is can get. Moreover, when the sealing member 3 for sealing is softened by doing in this way, the outer peripheral part of a panel can be sealed stably.
[0043]
Further, another embodiment of the present invention will be described with reference to the temperature profile shown in FIG. 8 and the panel and apparatus configuration shown in FIG.
[0044]
In this sealing step, the valve 9 is opened, and the dry gas is introduced into the panel through the second glass tube 7 when the panel is heated by the dry gas introduction device 6. Below the softening point temperature of the sealing member 3 for sealing, since the sealing member 3 for sealing is not softened, there are many gaps between the substrate and the gas introduced from the gap and below the softening point temperature. The impurity gas released from the substrate into the panel is discharged.
[0045]
Thereafter, the valve 9 is closed in the vicinity of the softening point temperature of the sealing material 3 for sealing, the introduction of the dry gas is stopped, and the outer periphery of the panel is sealed by heating to a temperature higher than the softening point temperature of the sealing material 3 for sealing. Keep the airtight inside the panel.
[0046]
Further, after the inside of the panel was kept airtight, the valve 10 was opened to start exhausting the panel through the first glass tube 5 and introducing dry gas through the second glass tube 7. In this step, the gas released from the front plate 1 and the back plate 2 above the softening point temperature of the sealing member 3 for sealing is replaced with the dry gas. As a result, water vapor is not confined in a narrow discharge space as in the conventional sealing process, and it becomes possible to suppress the deterioration of the blue phosphor during sealing, which has the greatest effect on reducing residual impurity gas. Can be obtained. In addition, since the gas flow is stopped near the softening point temperature of the low melting point glass and the panel sealing period is provided, the dry gas is passed through the panel after the panel is completely sealed and the glass tube is completely bonded. Sealing was performed stably by flowing.
[0047]
As the water vapor partial pressure of the dry gas, the lower the water vapor partial pressure, the more the deterioration of the blue phosphor is suppressed, but a remarkable effect appeared from around 10 Torr (1.33 kPa) as compared with the conventional sealing process.
[0048]
In addition, when oxide phosphors such as BaMgAl ₁₀ O ₁₇ : Eu, Zn ₂ SiO ₄ : Mn and (Y, Gd) BO ₃ : Eu, which are often used in PDP, are heated in an oxygen-free atmosphere. Some oxygen defects may be formed and the luminous efficiency may be lowered.
[0049]
Therefore, it is desirable that the dry gas used in the sealing process contains at least oxygen.
[0050]
Further, if the gas discharge and dry gas introduction start temperature starts from the sealing peak temperature, it is possible to completely suppress the sealing failure.
[0051]
In addition to the present embodiment, the gas introduction method includes providing a relief valve between the first glass tube and the exhaust device, introducing a dry gas from the second glass tube, and discharging it from the relief valve. The same effect can be obtained.
[0052]
Furthermore, even if only one of the first or second glass tube is provided, and the discharge of gas and the introduction of the dry gas are repeated from the glass tube, the same effect is obtained. However, in this case as well, it is necessary to heat the glass to a temperature equal to or higher than the softening point of the low-melting glass, and after the panel is completely sealed and the glass tube is completely adhered, the dry gas needs to flow through the panel.
[0053]
In addition, the evacuation process was completed efficiently by continuing to the panel evacuation step while keeping the panel sealed in these sealing processes at a high temperature.
[0054]
Further, when driving the PDP, as shown in FIG. 4, each driver and the panel drive circuit 100 are connected to the PDP and applied between the scan electrode 101a and the address electrode 102 of the cell to be lit to generate an address discharge. Then, a sustain discharge is performed by applying a pulse voltage between the display electrodes 101a and 101b. Then, ultraviolet light is emitted in the cell along with the discharge, and converted into visible light in the phosphor layer. When the cell is lit in this manner, an image is displayed.
[0055]
【Example】
In order to verify the effect of the present invention, a PDP was produced based on the above embodiment and compared with a conventional PDP. The panel is 42 "(inch) size.
[0056]
In the panel of this example, a glass frit having a softening point of 390 ° C. was used as a sealing material. The introduction of the dry gas into the panel was started from room temperature, and it was heated to 390 ° C. while flowing the dry gas into the panel. The drying gas flow rate was 1 sLm. When the panel temperature reached 390 ° C., the introduction of the drying gas was stopped, and the panel was heated to 450 ° C., which is the sealing peak temperature. At the same time as the panel temperature reaches 450 ° C. and keeping the sealing peak temperature is started, gas discharge from the panel is started, and introduction of dry gas into the panel is resumed. The dry gas flow rate at this time was 100 sccm.
[0057]
Note that dry air was used as the dry gas.
[0058]
The PDP according to the comparative example is a panel that is sealed without flowing dry gas through the panel as in the conventional sealing process.
[0059]
In each of the PDPs, the sealing step was a temperature profile that maintained a peak temperature of 450 ° C. for 10 minutes. The panel configuration was the same, the phosphor film thickness was 30 μm, and the discharge gas was enclosed in Ne (95%)-Xe (5%) at 500 Torr (66.5 kPa).
[0060]
In the panel evacuation process, which is the next process of the sealing process, the time for the inside of the panel to reach a predetermined degree of vacuum of 5 × 10 ⁻⁵ Pa is about 1/3 of the panel made by the conventional sealing process. The effect of shortening the lead time in the process was confirmed.
[0061]
The emission characteristics evaluated by turning on the panel include emission intensity (luminance divided by chromaticity coordinate y), chromaticity coordinate y, emission spectrum peak wavelength and blue, red, The color temperature (without color temperature correction) of white display when all the green lights were turned on under the same power condition was measured.
[0062]
As a result of the panel comparison, in the panel of this example, the blue emission intensity increased by 30% compared to the comparative example, and the blue chromaticity coordinate y also decreased to 0.06 (0.09 in the comparative example). Along with this, the white color temperature also improved to 11000K (comparative example 5800K). Furthermore, impurities in the panel were eliminated during sealing, and the discharge characteristics and uniformity in the panel were improved.
[0063]
Further, although not shown in the examples, regarding the water vapor partial pressure of the dry air flowing in the sealing device, the light emission characteristics improved as the water vapor partial pressure decreased.
[0064]
In the above embodiment, the surface discharge type PDP is exemplified, but the present invention can be applied to all PDPs that require a heat process for sealing, such as a counter discharge type PDP.
[0065]
【The invention's effect】
As described above, according to the present invention, it is possible to suppress the deterioration of the light emission characteristics of the phosphor that has occurred in the conventional sealing process in a stable process. As a result, the light emission intensity and the light emission efficiency are high, and the color reproduction range is reduced. A wide plasma display panel can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing a sealing process according to a first embodiment of the present invention. FIG. 2 is a panel in which a front plate and a back plate before sealing are bonded to each other according to the first embodiment of the present invention. FIG. 3 is a schematic sectional view of an AC surface discharge type plasma display panel according to the present embodiment. FIG. 4 is a diagram showing a PDP display device in which a drive circuit is connected to the PDP according to the present embodiment. 5 is a schematic cross-sectional view of a conventional AC surface discharge type plasma display panel. FIG. 6 is a diagram showing a sealing process according to a second embodiment of the present invention. FIG. 7 is a diagram showing a second embodiment of the present invention. The figure which shows the panel which bonded the front board and back board before sealing concerning a form, and an apparatus structure. [FIG. 8] The figure which showed the sealing process concerning another embodiment of the 2nd Embodiment of this invention. FIG. 9 relates to another embodiment of the second embodiment of the present invention. It shows a front panel and a panel and device configuration by bonding the back plate before wearing EXPLANATION OF REFERENCE NUMERALS
DESCRIPTION OF SYMBOLS 1 Front plate 2 Back plate 3 Sealing sealing material 4 Exhaust device 5 First glass tube 6 Drying gas introduction device 7 Second glass tube 8 Heating furnaces 9 and 10 Valves

Claims (7)

In the state where the front plate and the back plate on which the phosphor layer is formed on at least one and the sealing sealant layer is formed on at least one are overlapped so that an internal space is formed between both substrates, the inner space In a method for producing a plasma display panel, comprising a sealing step of sealing by maintaining a sealing temperature equal to or higher than a temperature at which the sealing sealing material softens (softening point) while flowing dry gas in
A method of manufacturing a plasma display panel, wherein a dry gas starts to flow into the internal space after the temperature becomes equal to or higher than a softening point of the sealing material.   2. The method of manufacturing a plasma display panel according to claim 1, wherein a dry gas starts to flow through the internal space when heated to a sealing peak temperature. In the state where the front plate and the back plate on which the phosphor layer is formed on at least one and the sealing sealant layer is formed on at least one are overlapped so that an internal space is formed between both substrates, the inner space A plasma comprising a sealing step of sealing by alternately maintaining an operation of filling a dry gas and an operation of discharging a gas from the internal space while maintaining a sealing temperature equal to or higher than a temperature at which the sealing material is softened. In the display panel manufacturing method,
The plasma display panel is characterized in that after the temperature becomes higher than the softening point of the sealing material, the operation of filling the internal space with a dry gas and the operation of exhausting the gas from the internal space are started alternately. Production method.   4. The method of manufacturing a plasma display panel according to claim 3, wherein, when heated to a sealing peak temperature, the operation of filling the internal space with a dry gas and the operation of discharging the gas from the internal space are alternately repeated. . The method for producing a plasma display panel according to claim 1 , wherein the dry gas contains at least oxygen. 6. The method of manufacturing a plasma display panel according to claim 5 , wherein the dry gas is made of dry air. The method for manufacturing a plasma display panel according to any one of claims 1 to 6 , wherein the partial pressure of water vapor of the dry gas is 133 Pa (1 Torr) or less.

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