JP2007335215A - Manufacturing method of plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a plasma display panel capable of suitably removing impurities from a protective layer and improving the product service life. <P>SOLUTION: In the manufacturing method of the PDP, a protective layer forming step S112 for forming the protective layer on a front substrate and a sealing step S140 for forming a sealed space between a back substrate and the front substrate by a seal frit are performed. Between the protective layer forming step S112 and the sealing step S140, an irradiation step S113 for applying plasma irradiation or ultraviolet ray irradiation on the protective layer formed on the front substrate and an impurity removal step for removing impurities discharged from the protective layer in the irradiation step S113 are performed. Impurities such as organic materials deposited on the surface of the protective layer can be positively removed from the protective layer, and the product service life of the PDP can be improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a plasma display panel in which a sealed space is formed between a pair of substrates arranged opposite to each other.

  A plasma display panel (PDP) includes a front substrate and a rear substrate which are a pair of glass substrates disposed to face each other via a discharge space. On the inner surface side of the front substrate, for example, a plurality of display electrodes, a plurality of black stripes, a dielectric layer, and a protective layer made of MgO (magnesium oxide) are provided. The inner surface of the rear substrate is filled with, for example, a plurality of address electrodes that are substantially orthogonal to the display electrodes of the front substrate, an address electrode protective layer, a partition that partitions the discharge space into a plurality of discharge cells, and the inside of the discharge cells. A phosphor layer of three primary colors of red (R), green (G), and blue (B) is provided. A discharge gas such as a rare gas is injected into the plurality of discharge cells, and an image can be displayed by selectively emitting light in each discharge cell.

Conventionally, in such a PDP manufacturing process, a protective layer forming step for forming a protective layer on the front substrate and a front substrate and a rear substrate that have undergone all the steps of manufacturing the front and back substrates are overlapped, and the substrate is interposed between these substrates. A sealing step of forming a sealed space including a discharge space by heating and softening and melting the provided sealing material made of low melting glass to a predetermined temperature and sealing the internal space between the substrates; There is something to implement.
For example, it is known to improve the quality of the MgO film by performing plasma irradiation on the MgO film formed through the protective layer forming step (see, for example, Patent Document 1).

JP 2000-87249 A (refer to page 5, FIG. 2, etc.)

  However, in the configuration described in Patent Document 1 described above, it is described that plasma irradiation is performed on the MgO film, but that alone is not sufficient in removing impurities attached to the MgO film. In particular, MgO is a material that easily adsorbs impurities, and if the PDP is panelized through the above sealing process with the impurities remaining in the MgO film, the product life may be reduced. The problem of being there is an example.

  In view of the above-described problems, it is an object of the present invention to provide a method for manufacturing a plasma display panel that can suitably remove impurities from a protective layer and improve product life.

  The invention according to claim 1 is a method of manufacturing a plasma display panel in which a sealed space is formed between a pair of substrates arranged opposite to each other, and a protective layer is formed on one of the pair of substrates. A protective layer forming step and a sealing material provided in a state surrounding the outer periphery of the protective layer between the pair of substrates to soften the sealing material at a predetermined temperature, and A sealing step of forming the sealed space by sealing the space, and the protective layer forming step between the protective layer forming step and the sealing step. An irradiation step of performing plasma irradiation or ultraviolet irradiation on the protective layer formed on one substrate and an impurity removing step of removing impurities discharged from the protective layer in the irradiation step are performed. It is characterized by Plasma is a manufacturing method of a display panel.

(1) 1st Embodiment Hereinafter, 1st Embodiment of this invention is described based on drawing.
FIG. 1 is a perspective view showing the internal structure of the PDP according to the first embodiment. FIG. 2 is a front view showing the appearance of the PDP. FIG. 3 is an enlarged plan view showing a part of the PDP. 4 is a side sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is a side sectional view taken along line V-V in FIG.
In these drawings, the dimensions of various electrodes and discharge cells are relatively large with respect to the substrate for the sake of simplicity of explanation, and the number thereof is omitted from the actual figure. In FIG. 2, the seal frit provided on the inner surface side of the front substrate in a plan view of the PDP is indicated by a solid line, and other components are omitted as appropriate.

(1-1) Configuration of Plasma Display Panel (PDP) In FIGS. 1 and 2, reference numeral 1 denotes a PDP. The PDP 1 is an apparatus that displays an image using light emission by plasma discharge. The PDP 1 includes a rear substrate 2 and a front substrate 3 which are a pair of substrates disposed to face each other with a discharge space H therebetween.

  The back substrate 2 is formed in a substantially rectangular shape with, for example, a glass plate material. On the inner surface of the rear substrate 2, as shown in FIG. 1, an address electrode 21, an address electrode protection layer 22, a partition wall 23, a phosphor layer (24R, 24G, 24B), and a vent hole 25 (see FIG. 2) and the like.

  The address electrode 21 is formed of a conductive material such as Al (aluminum), for example, in a straight line substantially along the direction (column direction) perpendicular to the longitudinal direction (row direction) of the back substrate 2 shown in FIG. A plurality are arranged at predetermined intervals in the direction.

  The address electrode protective layer 22 is formed of, for example, a dielectric paste or the like, and is provided over substantially the entire surface of the back substrate 2 so as to cover the address electrodes 21 as shown in FIGS. The address electrode protective layer 22 functions as a dielectric layer for preventing the wear of the address electrode 21 due to discharge and accumulating charges necessary for driving during panel driving.

  As shown in FIGS. 1 and 3, the partition wall 23 is formed, for example, in a substantially ladder shape with a dielectric paste having the same component as that of the address electrode protection layer 22. On the address electrode protective layer 22, a plurality of linear gaps S (FIG. 4) extending substantially along the row direction are arranged in parallel with each other. The partition wall 23 divides the discharge space H into a plurality of regions, thereby forming a plurality of rectangular discharge cells 231.

  As shown in FIGS. 1, 4 and 5, the phosphor layers (24R, 24G, 24B) are made up of red (R), green (G), and blue (B) sequentially filled in the plurality of discharge cells 231, respectively. It is a phosphor paste layer of three primary colors. These phosphor layers (24R, 24G, 24B) are excited by ultraviolet light when the discharge light is emitted from the respective discharge cells 231, and visible light of three primary colors of red (R), green (G), and blue (B). Is designed to emit light.

  The vent hole 25 is a through hole provided at one corner of the back substrate 2 as shown in FIG. A chip tube (not shown) is attached to the vent hole 25, and various kinds of the inside of the discharge space H are connected through the chip tube in a sealing process, an exhaust process, a gas introduction process, and an exhaust / gas replacement process to be described later. Gas is introduced and discharged.

  The front substrate 3 constitutes the display surface of the PDP 1 and is formed in a substantially rectangular shape with, for example, a glass plate material, like the rear substrate 2. On the inner surface of the front substrate 3, as shown in FIG. 1, a display electrode pair 31, a black stripe 32, a dielectric layer 33, a protective layer 34, and the like are provided.

  As shown in FIGS. 1, 3 to 5, the display electrode pair 31 includes a plurality of pairs of transparent electrodes 311 a and 311 b facing each other via a discharge gap G (see FIG. 3), and one end of the transparent electrodes 311 a and 311 b. A pair of linear bus electrodes 312a and 312b to be stacked is provided.

  As shown in FIG. 3, the transparent electrodes 311 a and 311 b are formed in a substantially T shape with a transparent conductive film such as ITO (Indium Tin Oxide), for example, and are provided in pairs corresponding to predetermined discharge cells 231. ing.

  The bus electrodes 312a and 312b are formed of a conductive material such as Ag (silver), for example, in a linear shape substantially along the column direction. And these bus electrodes 312a and 312b are each laminated | stacked and provided in the edge part on the opposite side with respect to the discharge gap G (refer FIG. 3) in a pair of transparent electrodes 311a and 311b.

  The black stripes 32 are formed linearly with, for example, a black inorganic pigment, and are provided between the plurality of display electrode pairs 31. The black stripes 32 absorb visible light irradiated from the outside of the front substrate 3.

  The dielectric layer 33 is formed of, for example, a dielectric paste, and is provided on the back substrate 2 at a position facing the address electrode protection layer 22 so as to cover the display electrode pair 31 and the black stripe 32. As shown in FIGS. 1 and 4, a raised dielectric layer 331 that protrudes toward the discharge space H is provided on the dielectric layer 33 facing the bus electrodes 312 a and 312 b. The raised dielectric layer 331 prevents erroneous discharge between the discharge cells 231 adjacent in the column direction.

The protective layer 34 is an MgO (magnesium oxide) layer formed by a film forming method such as a vapor deposition method or a sputtering method, and is provided in a state of covering substantially the entire surface of the dielectric layer 33. The protective layer 34 functions as a secondary electron emission layer for preventing the dielectric layer 33 from being sputtered by discharge and generating discharge at a low voltage.
A single crystal MgO layer (protective layer) (not shown) may be further formed on the protective layer 34 by a spray method. With such a single crystal MgO layer, it becomes possible to improve the discharge characteristics of PDP 1 (decrease in discharge delay and increase in discharge probability).

Between the back substrate 2 and the front substrate 3, a seal frit 4 (sealing agent) made of a material containing low-melting glass is provided along the periphery of the address electrode protection layer 22 as shown in FIG. It is provided in a state (a state surrounding the outer periphery of the protective layer 34). By this seal frit 4, the back substrate 2 and the front substrate 3 are integrated, and a sealed space including the discharge space H is formed between the back substrate 2 and the front substrate 3. The inside of this sealed space is in a reduced pressure state of about 6.7 × 10 ⁴ Pa (500 Torr), for example, and in the sealed space is a He—Xe (helium-xenon) system or a Ne—Xe (neon-xenon) system. Of inert gas.

(1-2) Manufacturing Method of PDP Next, a manufacturing method of the PDP 1 having the above configuration will be described mainly with reference to FIG. FIG. 6 is a flowchart showing the method for manufacturing the PDP according to the first embodiment.
In the first embodiment, as shown in FIG. 6, the manufacturing of the PDP 1 includes a front substrate manufacturing process S110, a back substrate manufacturing process S120, an overlaying process S130, a sealing process S140, and an exhaust process S150. It carries out by implementing gas introduction process S160.

  The front substrate manufacturing process S110 is a process for manufacturing the front substrate 3 having the above-described configuration. The front process S111, the protective layer forming process S112, the irradiation process S113, and the protective layer baking process S114 (impurity removing process) are performed. It is configured to include.

  In the pre-process S111, for example, a transparent electrode material layer is formed on the inner surface side of the sufficiently cleaned glass substrate, and the transparent electrodes 311a and 311b are patterned by a photolithography method or the like. Then, a conductive paste pattern is laminated and formed on the transparent electrodes 311a and 311b by a screen printing method or the like, and this is baked to form bus electrodes 312a and 312b. Thereafter, a black paste pattern is formed between the display electrode pairs 31 by screen printing or the like, and this is baked to form a plurality of black stripes 32. Further, a dielectric paste is applied so as to cover the display electrode pair 31 and the black stripe 32 by a die coater or the like, and this is baked to form the dielectric layer 33.

In the protective layer forming step S112, an MgO film as the protective layer 34 is formed on the dielectric layer 33 formed in the previous step S111 by a film forming method such as an evaporation method or a sputtering method.
In addition, it is good also as a structure which coat | covers the coating liquid containing single-crystal MgO by this spray method on this protective layer 34, and bakes this, and forms the single-crystal MgO layer (protective layer) which is not shown in figure.

In the irradiation step S113, plasma irradiation or UV irradiation is performed on the protective layer 34 formed in the protective layer forming step S112.
Specifically, when plasma irradiation is performed, for example, an atmospheric pressure plasma irradiation apparatus 5 as shown in FIG. 7 is used. That is, in the atmospheric pressure plasma irradiation apparatus 5, first, the front substrate 3 on which the protective layer 34 is formed is carried into the reaction vessel 51 by a conveying means (not shown), and the gas in the reaction vessel 51 is exhausted. Thereafter, the reaction gas g is introduced from the reaction gas supply means 52 to the high frequency electrode 53 and high frequency power is supplied to the high frequency electrode 53 from a high frequency power source (not shown). As a result, the reaction gas g is plasmatized with high-frequency power, and the plasmad reaction gas g is supplied to the protective layer 34.

By such plasma irradiation, impurities such as organic substances attached to the surface of the protective layer 34 can be discharged from the protective layer 34.
Here, as the reactive gas g, a mixture of 90% or more of an inert gas such as N ₂ , Ar, or He and 10% or less of O ₂ can be used. In this case, by mixing O ₂ in the reaction gas g, ozone can be generated with high-frequency power, and the effect of decomposing and cleaning impurities on the surface of the protective layer 34 with this ozone can be obtained. Moreover, modification effect of the MgO film surface is also obtained by the use of O _2. When the inert gas is less than 90% and the O ₂ is more than 10%, plasma cannot be generated satisfactorily.
In addition to the atmospheric pressure plasma irradiation device 5 described above, a similar effect can be obtained by using a reduced pressure plasma device for plasma irradiation.

  On the other hand, when UV irradiation is performed on the protective layer 34, a UV cleaning device (not shown) is used. In this UV cleaning apparatus, first, the front substrate 3 on which the protective layer 34 is formed is carried into the cleaning container by the transport means, and the gas in the cleaning container is exhausted. Thereafter, an atmospheric gas is introduced into the cleaning container from the gas supply means, and the protective layer 34 is irradiated with ultraviolet rays of 100 to 300 nm from the light irradiation means. Note that air may be used instead of the atmospheric gas.

By such UV irradiation, impurities such as organic substances attached to the surface of the protective layer 34 can be discharged from the protective layer 34.
Here, as the atmospheric gas, for example, a gas containing O ₂ can be used. In this case, ozone is generated by directly exciting O ₂ with ultraviolet rays, and the effect of decomposing / cleaning impurities on the surface of the protective layer 34 with this ozone is obtained. Moreover, the modification effect of the MgO film surface by O ₂ is also obtained.

In the protective layer baking step S114, the baking treatment is performed on the protective layer 34 (front substrate 3) after the plasma irradiation or the UV irradiation in the irradiation step S113. The firing temperature here is preferably 300 ° C. or higher and 700 ° C. or lower, more preferably 350 ° C. or higher and 450 ° C. or lower, from which impurities on the surface of the protective layer 34 are easily released. Note that when the firing temperature is lower than 300 ° C. or higher than 700 ° C., an excellent impurity release effect cannot be obtained.
By performing this protective layer baking step S114, impurities that have been decomposed by plasma irradiation or UV irradiation but still remain on the surface of the protective layer 34 can be removed. Further, the impurities once released from the protective layer 34 can be prevented from reattaching to the protective layer 34. And the product lifetime of PDP1 can be improved by forming into a panel using the front substrate 3 of this state. This has been confirmed in examples described later.

In the back substrate manufacturing step S120, the back substrate 2 having the above-described configuration is manufactured. That is, for example, an Al film is formed on the inner surface side of a sufficiently cleaned glass substrate, and the address electrode 21 is patterned by photolithography. Then, a dielectric paste is applied onto the address electrode 21, and the dielectric paste is formed and fired to form the address electrode protective layer 22 and the partition wall 23. Thereafter, a phosphor paste of three primary colors of red (R), green (G), and blue (B) is applied to the inside of the discharge cell 231 by a screen printing method or the like, and this is baked to phosphor layers (24R, 24G). , 24B).
For the back substrate 2 manufactured in this manner, for example, a paste obtained by kneading a low-melting glass powder with a resin such as acrylic and a solvent such as terpineol is used, as shown in FIG. It is provided in a state substantially along the periphery of the protective layer 22.

  In the overlaying step S130, the front substrate 3 manufactured in the front substrate manufacturing step S110 and the back substrate 2 manufactured in the back substrate manufacturing step S120 are overlapped with each other in a predetermined positional relationship.

  In the sealing step S140, the front substrate 3 and the rear substrate 2 superposed in the superposition step S130 are heated to a predetermined temperature (for example, about 450 ° C.) that is equal to or higher than the temperature at which the low melting point glass in the seal frit 4 is melted. Heat and maintain this temperature for a predetermined time to soften and melt the low melting point glass. Thereafter, the temperature is lowered to a temperature at which the low melting point glass is solidified, and the internal space between the front substrate 3 and the back substrate 2 is sealed. Thereby, a sealed space including the discharge space H is formed between the front substrate 3 and the rear substrate 2.

  In the exhaust step S150, the front substrate 3 and the rear substrate 2 are cooled to a temperature at which the seal frit 4 is solidified after the sealing step S140, and are formed in the sealing step S140 through the air holes 25 and a tip tube (not shown). The gas inside the sealed space is exhausted by a vacuum pump or the like. Thereby, impurities removed from the protective layer 34 in the protective layer baking step S114 and gas components such as resins and solvents contained in various structures are discharged from the sealed space.

In the gas introduction step S160, a discharge gas is introduced into the above-described sealed space through the vent hole 25 and a tip tube (not shown), and the inside of the space becomes, for example, about 6.7 × 10 ⁴ Pa (500 Torr). Adjust pressure to. Then, the tip of the tip tube is heated to melt the tip tube, and the tip tube itself is sealed.
Thus, the PDP 1 is completed.

(1-3) Operational Effects of PDP Manufacturing Method According to the above-described PDP 1 manufacturing method in the first embodiment, the following operational effects can be achieved.

(1-3-1) The manufacturing method of the PDP 1 in the present embodiment is to form a sealed space between the rear substrate 2 and the front substrate 3 arranged to face each other, and includes a protective layer forming step S112, and a sealing step S140. In the protective layer forming step S112, the protective layer 34 is formed on the front substrate 3. In the sealing step S140, the seal frit 4 provided between the back substrate 2 and the front substrate 3 is heated to soften the seal frit 4 at a predetermined temperature, and the internal space between the back substrate 2 and the front substrate 3 is sealed. By stopping, a sealed space is formed. Further, between the protective layer forming step S112 and the sealing step S140, an irradiation step S113 and an impurity removing step (protective layer baking step S114) are performed. In the irradiation step S113, plasma irradiation or ultraviolet irradiation is performed on the protective layer 34 formed on the front substrate 3 in the protective layer forming step S112. In the impurity removal step, the impurities discharged from the protective layer 34 in the irradiation step S113 are removed.
Thus, in the irradiation step S113, impurities such as an organic substance attached to the surface of the protective layer 34 can be discharged from the protective layer 34 by performing plasma irradiation or ultraviolet irradiation on the protective layer 34. Furthermore, by carrying out the impurity removal step, it is possible to remove impurities that have been decomposed by plasma irradiation or UV irradiation but still remain on the surface of the protective layer 34. Further, it is possible to prevent re-adhesion of the impurities once released to the protective layer 34. And by making into a panel using the front substrate 3 manufactured through such processes, it is possible to suppress erroneous discharge caused by impure gas during panel driving, and to maintain the display characteristics of the PDP 1 well. Can do. That is, the product life of the PDP 1 can be improved.

(1-3-2) The impurity removing step is a protective layer baking step S114 in which the protective layer 34 is baked.
As described above, in the protective layer baking step S114, by heating the front substrate 3, organic substances that have been decomposed by plasma irradiation or UV irradiation but still remain on the surface of the protective layer 34 can be removed. . Further, the impurities once released from the protective layer 34 can be prevented from reattaching to the protective layer 34. Therefore, impurities can be removed from the protective layer 34 more reliably.

(1-3-3) In the protective layer firing step S114, the front substrate 3 is heated at 300 ° C. or higher and 700 ° C. or lower.
In such a temperature range, the amount of impurities released from the protective layer 34 is large, so that the protective layer baking step S114 can be completed in a short time, thereby reducing the amount of power consumed during the production and the like. Improvement and reduction of manufacturing cost can be aimed at.

(1-3-4) The protective layer 34 is an MgO layer.
MgO is a substance that easily absorbs impurities. When the PDP 1 is manufactured with the impurities attached to the protective layer 34 made of MgO, erroneous discharge caused by the impurities occurs. In this respect, the impurity can be suitably removed by performing the irradiation step S113 and the impurity removal step, and the effect is more exhibited particularly when the protective layer 34 is formed of MgO.

(1-3-5) In the irradiation step S113, when the protective layer 34 is subjected to plasma irradiation, the reactive gas g is 90% or more of an inert gas such as N ₂ , Ar, or He, and 10% or less of O _2. It is preferable to use a mixture of
By using such a reactive gas containing O ₂ , ozone can be generated with high-frequency power, and organic substances on the surface of the protective layer 34 can be decomposed and washed with this ozone. That is, impurity removal efficiency can be improved. Moreover, the modification effect of the MgO film surface by O ₂ is also obtained.

(1-3-6) In the irradiation step S113, when the protective layer 34 is irradiated with UV, it is preferable to use a gas containing O ₂ as the atmospheric gas.
In this case, ozone can be generated by directly exciting O ₂ with ultraviolet rays, and organic substances on the surface of the protective layer 34 can be decomposed and washed with this ozone. That is, impurity removal efficiency can be improved. Moreover, the modification effect of the MgO film surface by O ₂ is also obtained.

(1-3-7) In the protective layer forming step S112, a coating solution containing single crystal MgO (not shown) is further applied on the protective layer 34 by a spray method, and this is baked to obtain a single crystal MgO layer ( The protective layer may be formed.
With such a single crystal MgO layer, it is possible to improve the discharge characteristics of PDP 1 (decrease in discharge delay, increase in discharge probability).
Here, when a single-crystal MgO layer is formed using a spray method, the solvent in the coating solution is removed by firing, but it cannot be completely removed by firing and remains slightly on the surface of the MgO layer. There is. In this regard, the solvent can also be reliably removed by performing the irradiation step S113 and the impurity removal step. Therefore, in addition to the effect of improving the discharge characteristics, the product life of the PDP 1 can be further improved.

(2) Second Embodiment Next, a second embodiment of the present invention will be described mainly based on FIG. FIG. 8 is a flowchart showing a method for manufacturing a PDP according to the second embodiment.
The second embodiment shown in FIG. 8 incorporates an exhaust / gas replacement step S240 instead of the protective layer firing step S114 as the impurity removal step in the method of manufacturing the PDP in the first embodiment shown in FIG. Is.

(2-1) PDP Manufacturing Method In the PDP 1 manufacturing method according to the second embodiment, as shown in FIG. 8, a front substrate manufacturing step S210, a back substrate manufacturing step S220, an overlaying step S230, an exhaust / A gas replacement step S240 (impurity removal step), a sealing step S250, an exhaust step S260 (secondary exhaust treatment step), and a gas introduction step S270 are performed. Moreover, in front substrate manufacturing process S210, pre-process S211, protective layer formation process S212, and irradiation process S213 are implemented.
In the second embodiment, the first step S211, the protective layer forming step S212, the irradiation step S213, the back substrate manufacturing step S220, the overlapping step S230, the sealing step S250, the exhausting step S260, and the gas introducing step S270 are the first step. Since the configuration is the same as the previous step S111, the protective layer formation step S112, the irradiation step S113, the back substrate manufacturing step S120, the overlay step S130, the sealing step S140, the exhaust step S150, and the gas introduction step S160 in the embodiment, The description is omitted.

  In the exhaust / gas replacement step S240, after the back substrate 2 and the front substrate 3 are heated to the softening start temperature of the seal frit 4, the primary exhaust process for exhausting from the internal space, and the replacement for introducing the replacement gas into the internal space Implement gas introduction treatment.

Specifically, first, in the baking furnace which is a baking apparatus for sealing, the back substrate 2 and the front substrate 3 superposed in the superposing step S230 are subjected to a softening start temperature of the seal frit 4 (for example, about 420 ° C.). ) Until heated. By softening the seal frit 4 in this manner, the internal space between the back substrate 2 and the front substrate 3 can be lightly sealed, but the subsequent primary exhaust treatment is surely performed. Is possible.
The softening start temperature of the seal frit 4 is within a temperature range of 350 ° C. or higher and 450 ° C. or lower where impurities on the surface of the protective layer 34 are particularly likely to be released. For this reason, the heat treatment can inevitably remove impurities that have been decomposed by the plasma irradiation or the UV irradiation in the irradiation step S213 but still remain on the surface of the protective layer 34. Further, the impurities once released from the protective layer 34 can be prevented from reattaching to the protective layer 34.

  In the primary exhaust treatment, immediately after heating to the softening start temperature as described above, the gas in the internal space between the back substrate 2 and the front substrate 3 is removed by a vacuum pump or the like through the vent hole 25 and a chip tube (not shown). Exhaust. Thereby, impurities removed from the protective layer 34 in the irradiation step S213 and gas components such as resins and solvents contained in various structures are discharged from the inside of the space.

In the replacement gas introduction process, after the exhaust process, the replacement gas is introduced into the internal space between the rear substrate 2 and the front substrate 3 through the vent hole 25 and a chip tube (not shown). The introduction pressure of the replacement gas is set to about 0.76 to 760 Torr, for example. Since the replacement gas is filled in the internal space in this way, it is possible to reliably prevent impurities from reattaching to the protective layer 34.
Here, a gas that does not contain H ₂ O and CO ₂ is used as the replacement gas. For example, one or more of inert gases such as Ar, H ₂ , O ₂ , N _2, and Cl ₂ are used. A gas composed of can be used. In particular, when the replacement gas used is a mixture of an inert gas and a trace amount of H ₂ (about 3% or less), the recovery effect of the phosphor layers (24R, 24G, 24B) can be obtained. Further, as a replacement gas, when using a mixture a small amount of O _{2 (about} 20% or less) in inert gas, it is possible to obtain the effect of improving the film quality of the protective layer 34.

  As described above, the exhaust / gas replacement step S240 can surely remove impurities from the surface of the protective layer 34 and can reliably prevent re-attachment of the impurities once released to the protective layer 34. In addition, since it is possible to reliably prevent the panel from being formed without impurities being sufficiently exhausted from the internal space, the product life of the PDP 1 can be further improved. This has been confirmed in the examples described later.

After the exhaust / gas replacement step S240, the sealing step S250, the exhaust step S260, and the gas introduction step S270 are performed as described above.
The exhaust / gas replacement step S240, the sealing step S250, the exhaust step S260, and the gas introduction step S270 may be performed by a series of processes in a baking furnace that is the same baking apparatus.
That is, in the exhaust / gas replacement step S240, the back substrate 2 and the front substrate 3 are heated to the softening start temperature (for example, about 420 ° C.) of the seal frit 4 in the baking furnace. Then, with this temperature maintained, the primary exhaust process and the replacement gas introduction process are performed, the temperature is further raised to the sealing operation temperature, and the sealing step S250 is continuously performed. At this time, since the softening of the seal frit 4 has started at the time of the exhaust / gas replacement step S240, the softening of the seal frit 4 can be sufficiently completed even if the heat treatment time in the sealing step S250 is relatively short, The processing time required for the sealing step S250 can be shortened. Thereafter, the temperature is lowered to a temperature at which the seal frit 4 is solidified, and the exhaust process S260 and the gas introduction process S270 are performed in the same baking furnace.
During these series of treatments, the temperature in the baking furnace is in a temperature range of 350 to 450 ° C. at which impurities on the surface of the protective layer 34 are particularly easily released, so that the impurities are more reliably removed from the protective layer 34. Since a sealed space can be formed to form a panel, the product life of the PDP 1 can be further improved.

(2-2) Effects of Manufacturing Method of PDP As described above, according to the manufacturing method of the PDP 1 of the second embodiment, the above (1-3-1), (1-3) In addition to the effects shown in -4) to (1-3-7), the following effects can be obtained.

(2-2-1) The impurity removal step includes a primary exhaust process in which the rear substrate 2 and the front substrate 3 are heated to a predetermined temperature and then exhausted from the internal space, and a replacement gas is introduced into the internal space. This is an exhaust / gas replacement step S240 for performing a gas introduction process.
By such an exhaust / gas replacement step S240, the impurities released from the protective layer 34 in the irradiation step S213 can be discharged from the internal space, and the once released impurities can be reliably prevented from reattaching to the protective layer 34. . As described above, since it is possible to reliably prevent a panel from being formed without impurities being exhausted sufficiently from the internal space, the product life of the PDP 1 can be further improved.
Further, according to this method, the above-described effects can be exhibited without setting each processing time of the primary exhaust processing and the replacement gas introducing processing to be long or using a large vacuum sealing device. Moreover, since the conventional manufacturing apparatus can be implemented with simple changes and modifications, the manufacturing cost does not increase significantly.

(2-2-2) In the exhaust / gas replacement step S240, the rear substrate 2 and the front substrate 3 are heated to the softening start temperature of the seal frit 4, and then the primary exhaust process and the replacement gas introduction process are performed.
Here, the softening start temperature of the seal frit 4 is within a temperature range of 350 to 450 ° C. at which impurities on the surface of the protective layer 34 are easily released. For this reason, the heat treatment in the exhaust / gas replacement step S240 inevitably removes impurities that have been decomposed by the plasma irradiation or the UV irradiation in the irradiation step S213 but still remain on the surface of the protective layer 34. it can. Further, the impurities once released from the protective layer 34 can be prevented from reattaching to the protective layer 34.
In addition, since the exhaust / gas replacement step S240 can be configured as a part of the sealing step S250, it is not necessary to provide a separate step for removing impurities from the protective layer 34, and the melting process of the seal frit 4 is performed. Outgassing can also be performed. Therefore, the manufacturing efficiency can be further improved.

(2-2-3) The exhaust / gas replacement step S240, the sealing step S250, the exhaust step S260 and the gas introduction step S270 may be performed by a series of processes in a baking furnace which is the same baking apparatus. .
In this case, during the above-described series of processing, the temperature in the baking furnace is within a temperature range of 350 to 450 ° C. at which impurities on the surface of the protective layer 34 are particularly likely to be released. A sealed space can be formed in the removed state to form a panel. Therefore, the product life of the PDP 1 can be further improved.

(2-2-4) In the replacement gas introduction process, a mixture of an inert gas and a trace amount of H ₂ (about 3% or less) is used as the replacement gas.
In this case, the recovery effect of the phosphor layers (24R, 24G, 24B) can be obtained.

(2-2-5) In the replacement gas introduction process, a mixture of an inert gas and a small amount of O ₂ (about 20% or less) is used as the replacement gas.
In this case, an effect of improving the film quality of the protective layer 34 can be obtained.

(3) Example Next, the Example for confirming the effect of the said embodiment is described.
(3-1) Effect of protective layer firing step A front substrate on which an MgO film is deposited by vapor deposition is prepared, the front substrate is heated to a temperature range of 60 to 800 ° C., and plasma irradiation is performed on the MgO film. (Example 1). At this time, the plasma irradiation was performed using a reduced pressure plasma irradiation apparatus, and the pressure in the reaction vessel was set to 60 kPa. Further, the reaction gas was used O _2.
And gas analysis was performed about the gas discharged | emitted from the reaction container in experiment. Qmass (Quadrupole Mass Spectrometer) was used for gas analysis. With this Qmass, it is possible to measure the partial pressure of a gas (hereinafter referred to as outgas (degassing)) released by decomposing organic substances remaining on the surface of the MgO film. The result is shown in FIG. In FIG. 9A, the vertical axis represents the partial pressure (Torr), and the horizontal axis represents the heating temperature (° C.). In the figure, the solid line corresponds to CO ₂ during outgas (degassing), and the one indicated by the alternate long and short dash line corresponds to CO during outgas (degas).
For comparison, the same front substrate as in Example 1 was prepared, and the front substrate was heated at 60 to 800 ° C. without performing plasma irradiation on the MgO film (Comparative Example 1). The outgas generated at this time was analyzed by Qmass. The result is shown in FIG. In FIG. 9B as well, the solid line in the figure corresponds to CO ₂ in outgas (degassing), and the one shown by the alternate long and short dash line corresponds to CO in outgas (degas).

9A and 9B, it can be said that the greater the partial pressure value at each heating temperature, the greater the amount of outgas (degassing) released, and the higher the organic substance removal efficiency on the MgO film surface.
As is clear from FIGS. 9A and 9B, when the plasma irradiation process is performed (Example 1), two types of outgas are compared with the case where the plasma irradiation process is not performed (Comparative Example 1). It can be seen that the amount of (degas) released is large as a whole, and organic substances attached to the MgO film are easily removed.
Further, when viewed by temperature, the amount of CO ₂ and CO released during outgassing (degassing) in Example 1 is large at 300 to 700 ° C, and among these, 350 to 450 ° C and 500 to 650 ° C further. You can see that it is increasing. In particular, the amount of CO ₂ and CO released at 350 to 450 ° C. is remarkably large. This is considered to be because organic substances are more easily released from the MgO film by heating in the above temperature range in addition to the plasma irradiation to the MgO film, and the reattachment of impurities once released is prevented. It is done.

From the above, it was found that organic substances attached to the MgO film can be suitably removed by performing the plasma irradiation treatment on the MgO film. Further, it was found that by performing heat treatment in addition to plasma irradiation on the MgO film, reattachment of impurities can be prevented and released impurities can be appropriately removed. Further, it was found that the impurity removal efficiency can be further improved by performing the heat treatment in a temperature range of 300 ° C. to 700 ° C., particularly 350 ° C. to 450 ° C.
These phenomena have been found to be the same even when the UV irradiation treatment is performed on the MgO film.

(3-2) Product Life The voltage life, which is one of the product life of PDP, was investigated for each of Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3 described below. FIG. 10 shows the result. In the figure, the vertical axis represents the voltage life for Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3, and the voltage life of Comparative Example 2-3 is expressed as a relative numerical value. ,
Here, the voltage life means a use time until a voltage value that can be driven by the PDP changes when the PDP is continuously driven and erroneous discharge occurs. In general, the change in the voltage value is such that impurities remaining in the discharge space of the PDP become impure gas and diffuse into the discharge gas as the product is used, and can be discharged until now. This is thought to be due to the fact that the voltage stops discharging. In other words, if the impurities in the panel (in the discharge space) are more reliably removed, it can be said that the voltage life is extended.

■ Example 2-1 (exhaust before sealing + plasma irradiation)
This is a PDP corresponding to the second embodiment described above. That is, as shown in FIG. 8, the PDP according to Example 2-1 includes a front substrate manufacturing process S210 including an irradiation process S213, a back substrate manufacturing process S220, an overlaying process S230, and an exhaust / gas replacement process. It produced by implementing S240, sealing process S250, exhaust process S260, and gas introduction process S270.
■ Example 2-2 (Normal sealing bake + MgO empty firing + plasma irradiation)
This corresponds to the first embodiment described above. That is, as shown in FIG. 6, the PDP according to Example 2-2 includes a front substrate manufacturing step S110 including an irradiation step S113 and a protective layer baking step S114, a back substrate manufacturing step S120, and an overlaying step S130. The sealing step S140, the exhaust step S150, and the gas introduction step S160 were performed.
■ Comparative Example 2-1 (normal sealing bake)
The PDP according to Comparative Example 2-1 was manufactured by superimposing immediately after forming the MgO film and through a sealing process and an exhaust process. That is, the manufacturing process of the first embodiment shown in FIG. 6 corresponds to the front substrate manufacturing process S110 excluding the irradiation process S113 and the protective layer baking process S114.
■ Comparative Example 2-2 (normal sealing bake + plasma irradiation)
The PDP according to Comparative Example 2-2 was manufactured through the sealing process and the exhausting process after the MgO film was formed, and after plasma irradiation, the PDP was superposed. That is, it corresponds to the manufacturing process of the first embodiment shown in FIG. 6 in which the protective layer baking process S114 is removed from the front substrate manufacturing process S110. That is, it corresponds to the technique described in Patent Document 1.
■ Comparative Example 2-3 (Exhaust before sealing)
The PDP according to Comparative Example 2-3 was manufactured through the primary exhaust / gas replacement process, the sealing process, and the secondary exhaust process, which were stacked immediately after the MgO film was formed. That is, it corresponds to the manufacturing process of the second embodiment shown in FIG. 8 in which the irradiation process S213 is excluded from the front substrate manufacturing process S210.

In FIG. 10, the voltage life of Example 2-1 is 1.40 times that of Comparative Example 2-3. From this, it can be seen that by performing the irradiation step S213, impurities can be reliably removed from the MgO layer, and the discharge life of the PDP can be significantly improved.
Moreover, the voltage life of Example 2-2 is 1.63 times the voltage life of Comparative Example 2-1. From this, it can be seen that by performing the irradiation step S113 and the protective layer firing step S114, impurities can be reliably removed from the MgO layer, and the discharge life of the PDP can be significantly improved.
Furthermore, it can be seen that the voltage life of Example 2-2 is 1.63 times that of Comparative Example 2-2. From this, it can be seen that by performing the protective layer firing step S114, impurities can be reliably removed from the MgO layer, and the discharge life of the PDP can be significantly improved.

(4) Modification of Embodiments The present invention is not limited to the above-described embodiments, and includes the following modifications as long as the object of the present invention can be achieved.

For example, in the above embodiment, the display electrode pair 31 and the dielectric layer 33 are provided on the front substrate 3 side, and the address electrode 21 and the phosphor layers (24R, 24G, 24B) are provided on the back substrate 2 side. Although the reflective AC PDP is illustrated, the present invention is not limited to this. That is, as a PDP to which the present invention can be applied, for example, a reflective AC in which a display electrode pair and an address electrode are formed on the front substrate side, and these are covered with a dielectric layer, and a phosphor layer is formed on the back substrate side. PDP may be used. Further, for example, a transmission AC PDP in which a phosphor layer is formed on the front substrate side, a display electrode pair and an address electrode are formed on the back substrate side, and these are covered with a dielectric layer may be used.
Moreover, although the said embodiment demonstrated and demonstrated the structure which forms the partition 23 in a cross-beam shape, it is good also as a structure which forms not only this but a partition in stripe form, for example. Further, although the raised dielectric layer 331 is provided on the dielectric layer 33, the raised dielectric layer 331 may not be provided on the dielectric layer 33.
That is, the present invention can be applied to any type of PDP as long as a protective layer is provided on either the front substrate or the back substrate.

  In the first embodiment, an example of the protective layer baking step S114 as the “impurity removing step” is given, and in the second embodiment, an example of the exhaust / gas replacement step S240 as the “impurity removing step” is given. As described above, both the protective layer firing step S114 and the exhaust / gas replacement step S240 may be implemented. In that case, the order is “protective layer firing step” → “overlaying step” → “exhaust / gas replacement step” → “sealing step”. According to such a configuration, impurities can be more reliably removed from the protective layer 34 than in the first and second embodiments, and the product life of the PDP can be further improved.

  In the said 1st Embodiment, although the example which implements irradiation process S113 and protective layer baking process S114 separately was given, it is good not only this but the structure which implements these simultaneously. That is, for example, the inside of the reaction vessel 51 shown in FIG. 7 or the mounting portion (not shown) of the front substrate 3 may be heated under the same temperature condition as in the protective layer baking step S114. In this case, as in the first embodiment, impurities can be removed from the protective layer 34. Furthermore, since both processes can be combined into one process, the working efficiency can be improved.

(5) Effects of Embodiment As described above, the method for manufacturing the PDP 1 in the above embodiment forms a sealed space between the back substrate 2 and the front substrate 3, and includes a protective layer forming step S112, It is comprised including wearing process S140. In the protective layer forming step S112, the protective layer 34 is formed on the front substrate 3. In the sealing step S140, the seal frit 4 provided between the back substrate 2 and the front substrate 3 is heated to soften the seal frit 4 at a predetermined temperature, and the internal space between the back substrate 2 and the front substrate 3 is sealed. By stopping, a sealed space is formed. Further, an irradiation step S113 and an impurity removal step are performed between the protective layer forming step S112 and the sealing step S140. In the irradiation step S113, plasma irradiation or ultraviolet irradiation is performed on the protective layer 34 formed on the front substrate 3 in the protective layer forming step S112. In the impurity removal step, the impurities discharged from the protective layer 34 in the irradiation step S113 are removed.
Thus, in the irradiation step S113, impurities such as an organic substance attached to the surface of the protective layer 34 can be discharged from the protective layer 34 by performing plasma irradiation or ultraviolet irradiation on the protective layer 34. Further, by performing the impurity removal step, it is possible to prevent the reattachment of impurities to the protective layer 34. By forming a panel using the front substrate 3 manufactured through such processes, it is possible to suppress the occurrence of erroneous discharge due to impure gas when the panel is driven, and to maintain the display characteristics of the PDP 1 well. . That is, the product life of the PDP 1 can be improved.

It is the perspective view which showed the internal structure of PDP in 1st Embodiment of this invention. It is the front view which showed the external appearance of PDP in the said 1st Embodiment. It is the top view which expanded and showed a part of PDP in the said 1st Embodiment. It is a sectional side view which follows the IV-IV line in FIG. It is a sectional side view which follows the VV line in FIG. It is a flowchart which shows the manufacturing method of PDP which concerns on the said 1st Embodiment. It is the schematic diagram which showed the atmospheric pressure plasma irradiation apparatus in the said 1st Embodiment. It is a flowchart which shows the manufacturing method of PDP which concerns on the said 2nd Embodiment. It is the graph which showed the gas analysis result in the Example of this invention, (A) is the analysis result about Example 1, (B) is the analysis result about the comparative example 1. FIG. It is the graph which showed the voltage life of PDP produced with each manufacturing method in the said Example.

Explanation of symbols

1 ... PDP
2 ... back substrate 3 ... front substrate 34 ... protective layer 4 ... seal frit H ... discharge space S110 ... front substrate manufacturing step S112 ... protective layer forming step S113 ... irradiation step S114 ... protective layer firing step (impurity removing step)
S120 ... Back substrate manufacturing process S140 ... Sealing process S210 ... Front substrate manufacturing process S212 ... Protective layer forming process S213 ... Irradiation process S220 ... Back substrate manufacturing process S240 ... Exhaust / gas replacement process (impurity removal process)
S250 ... Sealing step S260 ... Exhaust step (also a secondary exhaust treatment step)
S270 ... Gas introduction process

Claims (9)

A method for manufacturing a plasma display panel, wherein a sealed space is formed between a pair of substrates arranged opposite to each other,
A protective layer forming step of forming a protective layer on one of the pair of substrates;
Heating a sealing material provided in a state surrounding the outer periphery of the protective layer between the pair of substrates to soften the sealing material at a predetermined temperature, thereby sealing an internal space between the pair of substrates. A sealing step for forming the sealed space, and
Between the protective layer forming step and the sealing step,
An irradiation step of performing plasma irradiation or ultraviolet irradiation on the protective layer formed on the one substrate in the protective layer forming step;
An impurity removal step of removing impurities discharged from the protective layer in the irradiation step. A method for manufacturing a plasma display panel, comprising: In the manufacturing method of the plasma display panel of Claim 1,
The method for manufacturing a plasma display panel, wherein the impurity removing step is a protective layer baking step of baking the protective layer. In the manufacturing method of the plasma display panel of Claim 2,
In the protective layer baking step, the one substrate is heated at 300 ° C. or higher and 700 ° C. or lower. In the manufacturing method of the plasma display panel of Claim 1,
In the impurity removal step, after the pair of substrates are heated to a predetermined temperature, a primary exhaust process for exhausting from the internal space and a replacement gas introducing process for introducing a replacement gas into the internal space are performed. A method for manufacturing a plasma display panel, which is a gas replacement step. In the manufacturing method of the plasma display panel of Claim 4,
In the exhaust / gas replacement step, the primary exhaust process and the replacement gas introduction process are performed after heating the pair of substrates to the softening start temperature of the sealing material. . In the manufacturing method of the plasma display panel of Claim 5,
The exhaust / gas replacement step, the sealing step, a secondary exhaust treatment step for exhausting the gas in the sealed space after the sealing step, and a discharge gas in the sealed space after the secondary exhaust treatment step A method of manufacturing a plasma display panel, wherein the gas introduction step to be introduced is performed by a series of processes in the same baking apparatus. In the manufacturing method of the plasma display panel in any one of Claim 1 thru | or 6,
The said protective layer is a MgO (magnesium oxide) layer. The manufacturing method of the plasma display panel characterized by the above-mentioned. In the manufacturing method of the plasma display panel in any one of Claim 1 thru | or 7,
In the irradiation step, when plasma irradiation is performed on the protective layer, a gas in which 90% or more of an inert gas and 10% or less of O ₂ (oxygen) are mixed is used. Production method. In the manufacturing method of the plasma display panel in any one of Claim 1 thru | or 7,
In the irradiation step, when the protective layer is irradiated with ultraviolet rays, a gas containing O ₂ (oxygen) is used.

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