Patent Grant
7766713
The present invention relates, in general, to a method of manufacturing a barrier rib for a plasma display panel (PDP), and, more particularly, to a method of manufacturing a barrier rib for a PDP, which is advantageous because a barrier rib having a fine and complicated shape can be simply and precisely manufactured using a material, which can be cured at a low temperature and has fluidity, through a continuous process.
Generally, a barrier rib for a PDP is a structure formed in a dielectric layer, which is commonly provided on an electrode layer, formed on a rear glass substrate having address electrodes patterned to be parallel to each other. The barrier rib functions to maintain a discharge distance in the panel and to prevent electrical and optical interference between adjacent cells, and has a width of 40˜100 □ and a height of 50˜200 □.
In order to manufacture the barrier rib of a PDP, a frit material composed mainly of low melting point glass is used in a slurry or paste phase. Techniques for the formation of a barrier rib using such a material include, for example, a screen-printing process, a sandblasting process, a photolithographic process, and a molding process.
The paste or slurry of the frit material is prepared in the shape of a barrier rib and is then sintered at a high temperature of 500˜600° C. to cure the glass frit. When Pb, serving as a representative softening material, is not added, a sintering process should be conducted at a higher temperature. However, among barrier rib materials, Pb at 500° C. or higher acts as an environmental pollutant. In the case where large amounts of waste are generated, as when manufacturing the barrier rib of a rear substrate, costs of treatment of environmental pollutants and waste are increased. Further, repeated high-temperature process for use in manufacturing a barrier rib suffers because the dimensions of the glass substrate vary, a non-uniform pattern is formed, the defect rate of a PDP is increased, and the screen size of the panel is difficult to enlarge. Thus, the PDP substrate supporting the barrier rib should also be formed of specific glass which does not soften at high temperatures.
A conventional 42-inch panel has been manufactured by preparing a dielectric layer as high as the barrier rib using a screen-printing process and then forming a barrier rib structure using a sandblasting process. However, when manufacturing PDPs, such as HDTVs, having 60-inch panels or larger, not only smaller pitches between the structures but also flatness are required. Hence, a screen-printing process through multi-layer printing and a sandblasting process are unsuitable for the fabrication of complicated structures having accurate dimensions. With the aim of overcoming the complication of the process due to multi-layer screen printing and realizing the formation of uniform barrier ribs over the entire panel, Japanese Patent Laid-open Publication Nos. 9-102273 and 10-291834 disclose a method of manufacturing a barrier rib layer through a single process using a transfer film (a composite film comprising a film forming material layer formed using a glass paste composition and a support film, and a cover film laminated on the film forming material layer to be easily removed). Although this method is advantageous because the process is simple, it has the drawbacks, such as limited use of the sintered low melting point glass as a substrate, difficulty in the formation of a fine pattern structure, poor surface flatness, generation of large amounts of environmental waste, etc. Therefore, there is a need for the development of a material that may be formed into a thick film through a single process and may easily form fine patterns, in order to manufacture a PDP having a large area and high image quality.
In manufacturing a PDP barrier rib, in addition to a conventionally used sandblasting process, a mold- or roll-pressing process may be used, which is advantageous in terms of realizing excellent quality of the resultant barrier rib, simplified manufacturing processes, and decreased manufacturing costs. This process is conducted by applying a paste containing a barrier rib material on a glass substrate or a metal substrate such as titanium and then drying it, or by laminating a dry film, followed by pressing the dried paste or the dry film using a flat type mold or a cylindrical roll type mold having a pattern shape, which is opposite to that of a barrier rib, thereby forming a desired barrier rib. Technical contents regarding the above process are disclosed in Japanese Patent Laid-open Publication Nos. 11-185605 and 10-3265712, Japanese Patent Application No. 9-170148, and Korean Patent Application Nos. 1998-54538, 1998-21101, 1998-22675, and 1998-18584. Typically, the paste contains inorganic material (glass frit, loading ceramics (Al2O3, TiO2, ZrO2, etc.)) as the barrier rib material, and further includes organic material (solvent, binder, thixotropic agent, plasticizer, diluent, other additives) to obtain fluidity required for printing and pressing. The paste thus obtained is dried and then pressed using a flat type mold having a pattern shape, which is opposite to that of the barrier rib to be manufactured, to form a barrier rib, which is then removed from the mold and sintered. Subsequently, a phosphor is printed on side surfaces and a lower surface of the barrier rib, thus completing a rear substrate of a PDP. In these methods, however, the release of the mold from the formed barrier rib is difficult to assure.
Likewise, methods of manufacturing a barrier rib are proposed using a roll having grooves as a pattern having a shape opposite to that of a barrier rib, instead of the flat type mold. This method is conducted in a manner such that the dried paste or dry film is pressed in the shape of a barrier rib using the roll, and then sintered, thereby manufacturing a desired barrier rib.
Other than such mechanical pressing processes, Japanese Patent Application Nos. 9-165907 and 9-243523 and Korean Patent Application No. 1998-34029 disclose methods of manufacturing a barrier rib, comprising processing a metal or polymer material using a flat mold or roll or molding it using a photo etching process to have a pattern having a shape opposite to that of a barrier rib, loading a paste or slurry containing a barrier rib material into the pattern, drying the loaded paste or slurry and then removing the mold, which was proposed as a technique for forming a fine barrier rib. Further, grooves as a pattern corresponding to the shape of a barrier rib are formed through a photolithographic process or a mold pressing process, and are then filled with a barrier rib material. In this case, the filling procedure is carried out using a printing process using a squeezer or a tape casting process. After the barrier rib material is loaded, it is dried and laminated on a substrate having address electrodes printed thereon. The mold is released, and the barrier rib is sintered and is then printed on side surfaces and a lower surface thereof with the use of a phosphor, to manufacture a desired rear substrate of a PDP.
In the molding process, the problems regarding fluidity of the barrier material applied on the mold and, as well, reactivity between the barrier rib material and the mold, or release there between upon removing the mold from the formed barrier rib negatively affect the manufacture of the barrier rib. Further, when the mold is filled with the barrier rib material, all pattern grooves of the mold should be uniformly filled with the material in order to form a uniform barrier rib. When the mold is removed, the sintered barrier rib material in the patterns of the mold should have no reactivity with the mold in order to be easily released from the mold, to obtain non-degraded uniform barrier ribs. However, it is difficult to achieve such objects using the conventional methods.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a method of manufacturing a barrier rib for a PDP, in which a barrier rib having a fine and complicated shape can be simply and precisely manufactured from a material that may be cured at a low temperature of 300° C. or less and that has fluidity through a continuous process.
According to a first embodiment of the present invention for achieving the above object, a method of manufacturing a barrier rib for a plasma display panel is provided, comprising providing a silicon compound resin layer on a substrate; pressing the silicon compound resin layer using a master having a pattern corresponding to the shape of a barrier rib to transfer it; and curing the silicon compound resin and then releasing the master.
According to a second embodiment of the present invention, a method of manufacturing a barrier rib for a plasma display panel is provided, comprising loading a silicon compound resin into grooves of a master having a pattern corresponding to the shape of a barrier rib; pressing the master on a substrate to transfer the silicon compound resin to the substrate; and curing the transferred silicon compound resin and then releasing the master.
In the method according to the first and second embodiments of the present invention, the silicon compound resin preferably further comprises a pigment.
In the method according to the first and second embodiments of the present invention, the silicon compound resin preferably further comprises a UV curing agent or a heat curing agent.
In the method according to the first and second embodiments of the present invention, the silicon compound preferably comprises a compound including a compound material represented by Formula 1 below or by R6SiO1.5 as a repeating unit, or a polymer including the compound material as a monomer:
wherein X is an integer including 0, and R1, R2, R3, R4, R5, and R6 are each a linear, branched or cyclic C1-12 hydrocarbon group having a functional group selected from among an alkyl group, a ketone group, an acryl group, a methacryl group, an allyl group, an alkoxy group, an aromatic group, a halogen group, an amino group, a mercapto group, an ether group, an ester group, an alkoxy group, a sulfone group, a nitro group, a hydroxy group, a cyclobutene group, a carbonyl group, a carboxyl group, an alkyd group, a urethane group, a vinyl group, a nitrile group, hydrogen, an epoxy group, and mixtures thereof, and A is O or NH, in which the C1-12 hydrocarbon group includes fluorine substituted for hydrogen thereof.
In the method according to the first and second embodiments of the present invention, the pigment is preferably selected from the group consisting of ruthenium oxide, nickel oxide, titania, titania-alumina, iron oxide, titanium oxide, barium nitride, aluminum oxide, and mixtures thereof.
In the method according to the first and second embodiments of the present invention, the master is preferably a flat type or a roll type.
In addition, the present invention provides a plasma display panel, comprising a silicon compound resin and manufactured using the method according to the first embodiment or the second embodiment.
According to the present invention, a barrier rib composition in a liquid phase, which does not contain PbO and may be cured even at a low temperature not higher than 300° C., can be easily formed into a barrier rib through a transferring process using a master. Further, since the temperature of the curing process may be decreased, a soda lime glass substrate or a plastic substrate, suitable for curing at low temperature, may be used.
In addition, a silicon compound resin is used as a material for a barrier rib, and it is thus possible to precisely manufacture a barrier rib having a fine and complicated shape and to continuously manufacture the barrier rib. Upon manufacturing the barrier rib, the barrier rib material is not excessively used, thus generating less environmental pollution. Moreover, the manufacturing processes are simplified, resulting in reduced manufacturing costs.
Hereinafter, a detailed description will be given of the present invention.
Based on the present invention, a method of manufacturing a barrier rib composed mainly of a silicon compound resin through a transferring process using a master is provided. The transferring process using a flat type master or a roll type master is classified into a micro embossing process for applying a silicon compound resin layer on a rear substrate and then pressing the silicon compound resin layer, using the above master, to be transferred, and a stamping process for filling grooves of a master with a silicon compound resin, and pressing the master on a rear substrate to transfer the silicon compound.
The silicon compound used in the present invention is an organic-inorganic hybrid material, and preferably includes siloxane (—Si—O—) or silazane (—Si—NH—) as a main skeleton, in which any one of four bonding regions of a silicon atom is a linear, branched or cyclic C1-12 hydrocarbon group. More preferably, the silicon compound comprises a compound including a compound material represented by Formula 1 below or by R6SiO1.5 as a repeating unit, or a polymer including the compound material as a monomer:
wherein X is an integer including 0, and R1, R2, R3, R4, R5, and R6 are each a linear, branched or cyclic C1-12 hydrocarbon having a functional group selected from among an alkyl group, a ketone group, an acryl group, a methacryl group, an allyl group, an alkoxy group, an aromatic group, a halogen group, an amino group, a mercapto group, an ether group, an ester group, an alkoxy group, a sulfone group, a nitro group, a hydroxy group, a cyclobutene group, a carbonyl group, a carboxyl group, an alkyd group, a urethane group, a vinyl group, a nitrite group, hydrogen, an epoxy group, and mixtures thereof, and A is O or NH, in which the C1-12 hydrocarbon group includes fluorine atoms substituted for some hydrogen atoms thereof.
In this regard, examples of the silicon compound usable in the present invention include an organic-inorganic hybrid material disclosed in Korean Patent Laid-open Publication No. 2004-0013816.
In addition, the silicon compound resin composed of the above material may have at least one metal atom therein. The silicon compound having metal may be prepared by substituting a metal atom for a silicon atom of the structure shown in Formula 1, using a precursor formed of a metal atom, such as aluminum, titanium, zirconium or tin. Preferably, the silicon compound is composed of siloxane (—Si—O—) and metal oxide (-M-O—) uniformly linked together as a main skeleton, in which any one of three or more bonding regions of a silicon atom or a metal atom is a linear, branched or cyclic C1-12 hydrocarbon group. The silicon compound including the metal atom is advantageous because mechanical or thermal properties may be improved, and various changes of the optical properties may be realized.
Further, in order to confer durability and optical properties of a barrier rib to the silicon compound resin, a pigment is preferably used. The pigment is not particularly limited as long as it imparts durability and optical properties of the barrier rib, and includes both inorganic pigments and typically used pigments. The pigment is exemplified by black pigments, such as ruthenium oxide, nickel oxide, titania, titania-alumina, iron oxide, etc., and white pigments, such as titanium oxide, barium nitride, aluminum oxide, etc. Of the barrier rib materials, the inorganic pigment is used in an amount of 10˜60 wt %, based on the weight of the silicon compound. The properties of the barrier rib may be varied with the amount of the inorganic pigment.
Further, a curing agent is added to the silicon compound, to enable curing of the barrier rib material using UV light or heat, thereby manufacturing a barrier rib. The curing agent (or initiator) is not particularly limited, and may be appropriately selected depending on the type of silicon compound resin or the kind of heat or UV light. The exposure time is determined within a range that maintains the shape of a barrier rib and prevents a part of the barrier rib adhering to the master from being separated from the barrier rib when the master is removed.
A barrier rib material including the silicon compound thus prepared is applied or loaded between a master and a rear substrate, to be thus transferred onto a rear substrate having an electrode and a dielectric layer. The transferred barrier rib material is cured using UV light or heat, after which the master is removed from the rear substrate, to manufacture a barrier rib. A method of manufacturing a barrier rib according to the present invention is specifically described below.
The manufacturing method according to the first embodiment of the present invention using a flat type master is described with reference to
In addition, the manufacturing method according to the second embodiment of the present invention using a flat type master is described with reference to
In addition to the use of the flat type master in the manufacturing method according to the first embodiment or second embodiment of the present invention, a roll type master may be applied to manufacture the same barrier rib, which is described below, with reference to
The manufacturing method according to the first embodiment using a roll type master is described as shown in
In addition, the manufacturing method according to the second embodiment using a roll type master is described with reference to
The flat type master and the roll type master may be used alone or in combination. For example, the flat type master may be applied to the portion of the master where the silicon compound resin is applied or loaded or the portion of the master coming in contact with the rear substrate, while the master travels by the roll, thereby simultaneously using the flat type master and the roll type master.
Further, the pattern of the master, corresponding to the shape of the barrier rib, may vary. For example, a stripe type barrier rib may be formed in a manner such that the transfer direction of the master and the disposition of barrier ribs are controlled in the range of 0˜90° C. from the traveling direction of the master. In addition, it is easy to continuously manufacture a honeycomb or meandering type barrier rib.
The material for a master is not particularly limited as long as it may be used in all types including a roll type, a flat type, and a combination thereof.
A better understanding of the present invention may be obtained in light of the following examples which are set forth to illustrate, but are not to be construed to limit the present invention.
13.11 g of 3-glycidoxypropyltrimethoxysilane (Aldrich) and 10.05 g of diisobutylsilanediol were mixed together, added with 0.1 g of sodium hydroxide as a catalyst, and then allowed to react at 80° C. for 3 hr, to prepare a solution. The solution thus prepared was heated at 60° C. in a vacuum to extract all of the methanol, and then added with 0.1 g of UVI 6992 (DOW) as an epoxy initiator, to prepare a silicon compound resin containing a curing agent.
To the silicon compound resin, titania as an inorganic pigment was added in varying amounts of 20, 30, 40, 50 and 60 wt %. The properties of a barrier rib could be varied with the amount of titania, as shown in Table 1 below.
The silicon compound resin containing the curing agent and the pigment was subjected to a stamping process on a rear substrate using a master made of PDMS, as shown in the right side of
Subsequently, the master was released from the temporarily formed barrier rib and the rear substrate, after which the master was completely removed from the rear substrate. Thereby, the transferring process was completed, followed by a curing process at 200° C. for 3 hr, thus forming a final barrier rib having a height of 140 □, a thickness of 140 □ and cell pitches of 380 □ (
5 wt % of 2,5-dimethyl-2,5-t-butylperoxy hexane (Aldrich) as a curing agent was added to PDMS (MW: 28,000, Bayer) having a vinyl group, to prepare a silicon compound resin.
As in Example 1, titania as an inorganic pigment was added to the silicon compound resin in varying amounts of 20, 30, 40, 50 and 60 wt %. The properties of a barrier rib were confirmed to vary with the amount of titania as seen in Table 1.
The silicon compound resin containing the inorganic pigment and the curing agent was subjected to a process of stamping on a rear substrate using a roll type master made of stainless steel, as shown in the left side of
Subsequently, the roll type master was naturally removed from the temporarily formed barrier rib and the rear substrate while being rotated on the barrier rib and the rear substrate. Thereby, the transferring process was completed, followed by a curing process at 180° C. for 4 hr, thus forming a final barrier rib.
A barrier rib was manufactured in the same manner as in Example 1, with the exception that a different silicon compound resin was used. The silicon compound resin used in this Example was prepared as follows.
That is, 13.11 g of 3-methacryloxypropyl trimethoxysilane (Aldrich) and 10.05 g of diisobutylsilanediol were mixed together, added with 0.1 g of sodium hydroxide as a catalyst, and then allowed to react at 80° C. for 3 hr, to prepare a solution. The reaction solution was added with 0.25 g of 2,2-dimethoxy-2-phenyl-acetophenone (Aldrich) as a UV curing initiator, to prepare a silicon compound resin. To the silicon compound resin thus prepared, titania as an inorganic pigment was added in varying amounts of 20, 30, 40, 50 and 60 wt %.
A barrier rib was manufactured in the same manner as in Example 2, with the exception that a different silicon compound resin was used. The silicon compound resin used in this Example was prepared as follows.
That is, 9.417 g of epoxycyclohexylisobutyl-polysilsesquioxane (MW: 1026, Aldrich) and 3.664 g of bis(3,4-epoxycyclohexylmethyl)adipate (Aldrich) were dissolved in 10 g of tetrahydrofuran and then stirred at room temperature for 3 hr. Aluminum 2-butoxide as an initiator was added in an amount of 5 wt % based on the total amount of the epoxy group, to prepare a silicon compound resin. To the silicon compound resin thus prepared, titania as an inorganic pigment was added in varying amounts of 20, 30, 40, 50 and 60 wt %.
13.78 g of 3-methacryloxypropyltrimethoxysilane (Aldrich) and 12.00 g of diphenylsilancdiol (Fluka) were mixed together, added with 0.1 g of sodium hydroxide as a catalyst for the acceleration of a siloxane reaction, and then stirred at 80° C. for 6 hr, to prepare a silicon compound resin. The silicon compound resin thus prepared was added with 6.7 g of titania as an inorganic pigment and 0.25 g of 2,2-dimethoxy-2-phenyl-acetophenone (Aldrich) as a photoinitiator for acryl curing.
The silicon compound resin thus obtained was used to manufacture barrier ribs according to the four methods shown in
13.78 g of 3-glycidoxypropyltrimethoxysilane (Aldrich) and 12.00 g of diphenylsilanediol (Fluka) were mixed together, added with 0.1 g of sodium hydroxide as a catalyst for the acceleration of a siloxane reaction, and then stirred at 80° C. for 6 hr, to prepare a silicon compound, which was then added with 6.7 g of titania as an inorganic pigment and 0.25 g of 1-methylimidazole (Aldrich) as a heat initiator for epoxy curing.
The silicon compound resin thus obtained was used to manufacture barrier ribs according to the four methods shown in
5.78 g of 3-glycidoxypropyltrimethoxysilane (Aldrich), 7.87 g of 3-methacryloxypropyltrimethoxysilane (Aldrich), and 12.00 g of diphenylsilanediol (Fluka) were mixed together, added with 0.1 g of sodium hydroxide as a catalyst for the acceleration of a siloxane reaction, and then stirred at 80° C. for 6 hr, to prepare a silicon compound resin. The silicon compound resin thus prepared was added with 6.7 g of titania as an inorganic pigment and 1.36 g of bisphenol-A (Aldrich) in 20 g of toluene, and then with 0.25 g of 1-methylimidazole (Aldrich) as a heat initiator for epoxy curing.
The silicon compound resin thus obtained was used to manufacture barrier ribs according to the four methods shown in
A silicon compound resin was prepared and then a barrier rib was manufactured in the same manner as in Example 5, with the exception that 10.33 g of 3-methacryloxypropyltrimethoxysilane (Aldrich) and 3.45 g of zirconium tetraisopropoxide were used, instead of 13.78 g of 3-methacryloxypropyltrimethoxysilane (Aldrich).
A silicon compound resin was prepared and then a barrier rib was manufactured in the same manner as in Example 6, with the exception that 10.33 g of 3-glycidoxypropyltrimethoxysilane (Aldrich) and 3.45 g of zirconium tetraisopropoxide were used, instead of 13.78 g of 3-glycidoxypropyltrimethoxysilane (Aldrich).
A silicon compound resin was prepared and then a barrier rib was manufactured in the same manner as in Example 5, with the exception that 9.83 g of 3-methacryloxypropyltrimethoxysilane (Aldrich) and 3.28 g of titanium tetraethoxide were used, instead of 13.11 g of 3-methacryloxypropyltrimethoxysilane (Aldrich).
A silicon compound resin was prepared and then a barrier rib was manufactured in the same manner as in Example 6, with the exception that 9.83 g of 3-glycidoxypropyltrimethoxysilane (Aldrich) and 3.28 g of titanium tetraethoxide were used, instead of 13.11 g of 3-glycidoxypropyltrimethoxysilane (Aldrich).
A silicon compound resin was prepared and then a barrier rib was manufactured in the same manner as in Example 7, with the exception that 4.28 g of 3-glycidoxypropyltrimethoxysilane (Aldrich), 1.5 g of zirconium tetraisopropoxide, 5.9 g of 3-methacryloxypropyl trimethoxysilane (Aldrich), and 1.97 g of titanium tetraethoxide were used, instead of 5.78 g of 3-glycidoxypropyltrimethoxysilane (Aldrich) and 7.87 g of 3-methacryloxypropyltrimethoxysilane (Aldrich).
A silicon compound resin was prepared and then a barrier rib was manufactured in the same manner as in Example 7, with the exception that 1.95 g of methacrylic acid (Aldrich), 2.3 g of 3-methacryloxypropyl trimethoxysilane (Aldrich), and 7.87 g of 3-glycidoxypropyltrimethoxysilane (Aldrich) were used, instead of 5.78 g of 3-glycidoxypropyltrimethoxysilane (Aldrich) and 7.87 g of 3-methacryloxypropyl trimethoxysilane (Aldrich).
A silicon compound resin was prepared and then a barrier rib was manufactured in the same manner as in Example 7, with the exception that 4.28 g of 3-glycidoxypropyltrimethoxysilane (Aldrich), 1.5 g of zirconium tetraisopropoxide, 0.95 g of methacrylic acid (Aldrich), 3.3 g of 3-methacryloxypropyltrimethoxysilane (Aldrich), and 1.97 g of titanium tetraethoxide were used, instead of 5.78 g of 3-glycidoxypropyltrimethoxysilane (Aldrich) and 7.87 g of 3-methacryloxypropyl trimethoxysilane (Aldrich).
A silicon compound resin was prepared and then a barrier rib was manufactured in the same manner as in Examples 5 to 15, with the exception that 13.56 g of diphenyldimethoxysilane (Fluka) and 2 g of water for hydrolysis and condensation were used, instead of diphenylsilanediol.
As described hereinbefore, the present invention provides a method of manufacturing a barrier rib for a PDP. According to the method of the present invention, a barrier rib composition in a liquid phase, which does not contain PbO and may be cured even at a low temperature not higher than 300° C., can be easily formed into a barrier rib through a transferring process using a master. Further, since the temperature of the curing process may be decreased, a soda lime glass substrate or a plastic substrate, suitable for low temperatures, may be used.
In addition, a silicon compound resin is used as a material for a barrier rib, and it is thus possible to precisely manufacture a barrier rib having a fine and complicated shape and to continuously manufacture the barrier rib. Upon manufacturing of the barrier rib, the barrier rib material is not excessively used, thus generating less environmental pollution. Moreover, the manufacturing processes are simplified, resulting in reduced manufacturing costs.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2005-0032475 | Apr 2005 | KR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/KR2006/000404 | 2/3/2006 | WO | 00 | 10/11/2007 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2006/112591 | 10/26/2006 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5541479 | Nagakubo | Jul 1996 | A |
| 5853446 | Carre et al. | Dec 1998 | A |
| Number | Date | Country |
|---|---|---|
| 09-102273 | Apr 1997 | JP |
| 10-291834 | Nov 1998 | JP |
| 10-326571 | Dec 1998 | JP |
| 11-016488 | Jan 1999 | JP |
| 11-016490 | Jan 1999 | JP |
| 11-071130 | Mar 1999 | JP |
| 11-185605 | Jul 1999 | JP |
| 10-1999-0085890 | Dec 1999 | KR |
| 1020000001058 | Jan 2000 | KR |
| 1020000002099 | Jan 2000 | KR |
| 1020000014546 | Mar 2000 | KR |
| 100304888 | Jul 2001 | KR |
| Number | Date | Country | |
|---|---|---|---|
| 20090085482 A1 | Apr 2009 | US |
