Patent Application
20080231186
This application claims the benefit of the Korean Patent Application No. P 10-2007-0027184, filed on, Mar. 20, 2007, which is hereby incorporated by reference as if fully set forth herein.
1. Field
This disclosure relates to a plasma display panel, which may have a barrier rib, a method for forming the same, and related technologies.
2. Discussion of the Related Art
With the advent of a multimedia age, there is a rising demand for the appearance of a more delicate and larger display device capable of representing colors closer to natural colors. Current cathode ray tubes (CRTs) are generally limited in their application to large-scale screens of 40 inches or more. Consequently, liquid crystal displays (LCDs), plasma display panels (PDPs), projection televisions (TVs), etc. are now being used for large-scale screens and high-definition imaging fields of larger size.
Characteristics of the above-mentioned display devices including the PDP are that the display devices can be manufactured with a thinner thickness than the self-luminous CRT, achieve easy manufacture of a flat large-scale screen (for example, 60˜80 inches), and be clearly distinguished from the conventional CRT with respect to style or design.
The PDP includes a lower panel having address electrodes, an upper panel having sustain electrode pairs, and discharge cells defined by barrier ribs. A phosphor is coated in each of the discharge cells, to display an image. More specifically, if a discharge occurs in a discharge space between the upper panel and the lower panel, ultraviolet rays generated by the discharge are incident to the phosphor to produce visible rays. With the visible rays, an image can be displayed.
The barrier ribs of the plasma display panel can be formed using a screen printing method, sanding method, photosensitive method, etching method, or the like. Here, the photosensitive method has an advantage of more simple manufacture than the sanding method or etching method, although it uses relatively expensive materials.
However, the above-described conventional methods for forming the barrier ribs of the plasma display panel have several problems, which may include one or more of the following.
A photosensitive barrier rib material includes an inorganic material, such as for example glass powder, linked with an organic material such as for example a binder and dispersant. However, when light is incident to the top of the photosensitive barrier rib material, it is possible that the photosensitive barrier rib material may not transmit the light to the bottom thereof due to a refractive index difference between the inorganic material and the organic material. More specifically, in one example, the inorganic material in the photosensitive barrier rib material has a refractive index of about 1.4 to 1.7, and the organic material has a refractive index of about 1.4 to 1.55. During an exposure process, such a refractive index difference between the inorganic material and the organic material causes light to be diffused, rather than reaching the bottom of the barrier rib material. As a result, in this example, the bottom of the barrier rib material cannot achieve a sufficient exposure efficiency.
As shown in
In one implementation, it is possible to address this issue by reducing a refractive index difference between inorganic and organic materials constituting the barrier rib material. For instance, a refractive index of the inorganic material may be decreased, and a refractive index of the organic material may be increased. However, it is actually difficult to find materials satisfying the above requirement. Moreover, although an acrylate-based organic material, in which a bulky group is attached to a side chain, may be used in order to increase the refractive index of the organic material, its use may increase a binder burn out (BBO) temperature of the organic material.
Implementations may include a plasma display method and a method for manufacturing the same that substantially obviates one or more problems due to the above or other limitations and/or disadvantages of the related art.
A plasma display panel and a method for manufacturing the same may involve inorganic and organic materials constituting a barrier rib, which have a small refractive index difference.
Furthermore, a method for manufacturing a plasma display panel may involve a photosensitive barrier rib material containing or including a hybrid binder.
Moreover, in one aspect, a method for manufacturing a plasma display panel includes forming address electrodes and a first dielectric layer on a first side of a first substrate; positioning barrier ribs by stacking a photosensitive barrier rib material, including a hybrid binder, on the first side of the first substrate, and processing the stacked photosensitive barrier rib material; positioning phosphor layers in respective cells defined by the barrier ribs; sequentially positioning at least one pair of transparent and bus electrodes, a second dielectric layer, and a protective layer on a first side of a second substrate; and fixing a position of the first substrate relative to a position of the second substrate, with the first side of the first substrate facing the first side of the second substrate.
In accordance with another aspect, there is provided a method for manufacturing a plasma display panel includes positioning a first dielectric layer material, including a hybrid binder, on a first side of a first substrate and address electrodes; stacking a photosensitive barrier rib material, including a hybrid binder, on the first dielectric layer material, and externally exposing and developing the stacked photosensitive barrier rib material; simultaneously baking the first dielectric layer material and barrier rib material, to form a first dielectric layer and barrier ribs; positioning phosphor layers in respective cells defined by the barrier ribs; sequentially positioning at least one pair of transparent and bus electrodes, a second dielectric layer, and a protective layer on a second substrate; and fixing a position of the first substrate relative to a position of the second substrate, with the first side of the first substrate facing the first side of the second substrate.
Exemplary implementations of these methods include various aspects. Specifically, for example, the photosensitive barrier rib material is formed by preparing an inorganic material linked with hydroxyl ions, and synthesizing the inorganic material with an acrylate-based binder. The acrylate-based binder is 3-(Trimethoxysilyl) propyl methacrylate and/or 3-Glycidoxypropyltrimethoxysilane. Also, the inorganic material may be linked with the hydroxyl ions using a negative ion polymerization, and the barrier rib material may further includes an inorganic material, where a refractive index difference between the inorganic material and the acrylate-based binder is 0.15 to 0.2. The photosensitive barrier rib material may be stacked by laminating the photosensitive barrier rib material in the form of a green sheet on the first substrate, and the stacked photosensitive barrier rib material may be processed by externally exposing and developing the photosensitive barrier rib material, and then, by baking the developed photosensitive barrier rib material. The developed photosensitive barrier rib material may be baked at a temperature of 550˜600° C. The phosphor layers may be positioned in respective cells defined by the barrier ribs by coating phosphor on the first dielectric layer and side surfaces of the barrier ribs.
Additionally, in accordance with another aspect, there is provided a plasma display panel including a first panel including address electrodes, a first dielectric layer, and phosphor layers positioned on a first side of a first substrate; a second panel including sustain electrode pairs, a second dielectric layer, and a protective layer positioned on a first side of a second substrate; and barrier ribs provided between the first panel and the second panel and including a parent glass and filler as an inorganic material, and acrylate-based binder.
Implementations of this plasma display panel include various aspects. Specifically, for example, the barrier ribs include 0.01˜0.06 wt % of the acrylate-based binder. Also, a refractive index difference between the inorganic material and the acrylate-based binder may be 0.15 to 0.2, and the barrier ribs may have a refractive index of 1.4 to 1.6. The acrylate-based binder may be at least one of 3-(Trimethoxysilyl) propyl methacrylate and 3-Glycidoxypropyltrimethoxysilane. And, the first dielectric layer may include a parent glass, filler, and acrylate-based binder.
The accompanying drawings, which are included to provide a further understanding and are incorporated in and constitute a part of this disclosure, illustrate aspects of the technologies disclosed. In the drawings:
In the drawings, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Also, in the drawings, dimensions of layers and regions may be exaggerated for clarity of description, and a thickness ratio between neighboring layers shown in the drawings may not be intended to represent an actual thickness ratio.
A plasma display panel may be configured in such a manner that an upper panel and a lower panel are bonded with each other while interposing barrier ribs therebetween.
As shown in
The front substrate 170 is formed, for example, by milling and cleaning a glass for a display substrate. Here, the transparent electrodes 180a and 180b are formed, for example, by a sputtering and photo-etching method or a chemical vapor deposition (CVD) and lift-off method of indium tin oxide (ITO) or SnO2. The bus electrodes 180a′ and 180b′ are formed of, for example, silver (Ag). Additionally, a black matrix can be formed on the sustain electrode pairs. The black matrix is formed of a low-melting-point glass, black pigment, etc.
The upper dielectric layer 190 is formed on the front substrate 170, which was formed with the transparent electrode 180a and 180b and bus electrodes 180a, and 180b′. Here, the upper dielectric layer 190 is formed of a transparent low-melting-point glass, and a detailed composition thereof will be described hereinafter. Then, the protective layer 195 is formed on the upper dielectric layer 190 using magnesium oxide, etc. The protective layer 195 serves to protect the upper dielectric layer 190 from a positive (+) ion shock caused during a discharge, and to increase a discharge efficiency of secondary electrons.
Meanwhile, the plasma display panel further includes a back substrate 110, which is formed at a surface thereof with address electrodes 120 extending in a direction orthogonal to the sustain electrode pairs. A white dielectric layer 130 is formed over the back substrate 110, to cover the address electrodes 120. The white dielectric layer 130 is formed by coating a dielectric material using a printing method or film laminating method, and baking the coated dielectric material. Then, barrier ribs 140 are formed on the white dielectric layer 130 such that they are arranged between the respective neighboring address electrodes 120. The barrier ribs 140 can be of a stripe-type, well-type, or delta-type.
Here, the barrier ribs 140 are formed of an inorganic material such as, for example, a parent glass and filler, and an organic material such as for example a solvent, binder and dispersant. The parent glass is classified into a lead-based parent glass and a lead-free parent glass. The lead-based parent glass includes ZnO, PbO, B2O3, etc., and the lead-free parent glass includes ZnO, B2O3, BaO, SrO, CaO, etc. Also, the filler is any one of SiO2, Al2O3, ZnO, TiO2, etc.
Most organic materials are almost removed during a baking process, but an acrylate-based binder can be left partially. This is because, in the case of a hybrid binder, organic and inorganic materials are linked with each other such that the organic and inorganic materials define a network, thereby preventing the organic material from being completely removed during a baking process. That is, as a result of linking a binder having properties of an organic material with an inorganic material, it is possible to solve a problem of the above described large refractive index difference of the photosensitive barrier rib material without adjusting refractive indices of organic and inorganic materials constituting the photosensitive barrier rib material. The hybrid hinder has a feature that an acrylate-based binder is linked with a parent glass, etc. as a constituent material of a barrier rib.
Now, a method for forming a hybrid binder will be described with reference to
First, as shown in
To link the inorganic material with a binder that will be described hereinafter, the inorganic material is synthesized with hydroxyl ions (OH−) using a negative ion polymerization. More specifically, the inorganic material is linked with hydroxyl ions (OH−) for encapsulation thereof. It is known that a general synthesizing method achieves only a yield of about 10%, but the negative ion polymerization can achieve a yield of about 90% under a vacuum condition.
After preparing the inorganic material by the above described method as shown in
With the above described process, a hybrid binder can be synthesized. The hybrid binder contains the inorganic material and organic binder linked with each other, and has a refractive index of 1.4 to 1.6. The hybrid binder can achieve a small refractive index difference between the inorganic material and the organic binder, as compared to a conventional binder obtained by synthesizing inorganic and organic materials. More specifically, a refractive index difference between the above described inorganic material and acrylate-based binder is about 0.15 to 0.2. The above described photosensitive barrier rib material has a BBO temperature of 450˜500° C., thereby allowing the organic material thereof to be completely removed during a baking process that is performed to form the barrier ribs of the plasma display panel. That is, in the case of the conventional photosensitive barrier rib material, although a bulky group should be attached to a side chain to increase a refractive index of the organic material, this results in a barrier rib material in the form of a paste, and the resulting barrier rib material suffers from a raised BBO temperature. The barrier rib material has the effect of solving a problem of the raised BBO temperature.
More specifically, the resulting barrier rib contains 0.1˜0.2% of an organic material component. In turn, the organic material component contains 0.01˜0.06% of the acrylate-based binder.
Although not shown, a black top can be formed on the barrier ribs 140. Red (R), green (G), and blue (B) phosphor layers 150a, 150b, and 150c are formed between the respective neighboring barrier ribs 140. Locations where the address electrodes 120 on the back substrate 110 intersect the sustain electrode pairs on the front substrate 170 are regions defining discharge cells, respectively.
The front substrate 170 and the back substrate 110 are bonded with each other while interposing the barrier ribs 140 therebetween by use of a sealing material provided along the outline of the substrate.
Also, an upper panel including the front substrate 170 and a lower panel including the back substrate 110 are connected with a driving apparatus.
As shown, a plasma display device includes a panel 220, a driving substrate 230 to supply a driving voltage to the panel 220, and a tape carrier package 240 (hereinafter, referred to as a “TCP”) as one kind of a soft substrate that connects electrodes in relation to respective cells of the panel 220 with the driving substrate 230. Here, the panel 220, as described above, includes the front substrate, back substrate, and barrier ribs.
Electrical and physical connections between the TCP 240 and the panel 220 and electrical and physical connections between the TCP 240 and the driving substrate 230 are obtained by use of an anisotropic conductive film (hereinafter, referred to as “ACF”). The ACF is a conductive resin film formed using nickel (Ni) balls each coated with gold (Au).
As shown, the TCP 240 serves to connect the panel 220 and the driving substrate 230 with each other, and is equipped with a driving driver chip. The TCP 240 includes a wiring 243 densely arranged on a soft substrate 242, and a driving driver chip 241 connected with the wiring 243 and adapted to supply power transmitted from the driving substrate 230 to a specific electrode on the panel 220. Here, since the driving driver chip 241 is configured to alternately output many high-power signals upon receiving low voltages and driving control signals, it has a small number of wiring connected with the driving substrate 230 and a large number of wiring connected with the panel 220. As a result, the wiring connection of the driving driver chip 241 is accomplished through a space toward the driving substrate 230. Also, the wiring 243 may be not bounded about the center of the driving driver chip 241.
In the present implementation, the panel 220 is connected with the driving apparatus through a flexible printed circuit 250 (hereinafter, referred to as a “FPC”). Here, the FPC 250 is a film having an interior pattern formed of polyimide. Similarly, in the present implementation, the FPC 250 and the panel 220 are connected with each other by the ACF. Of course, in the present implementation, the driving substrate 230 is a PCB circuit.
The driving apparatus includes, for example, a data driver, a scan driver, and a sustain driver. The data driver is connected with address electrodes, to apply a data pulse. The scan driver is connected with scan electrodes, to supply a Ramp-up waveform, Ramp-down waveform, scan pulse, and sustain pulse. The sustain driver applies a sustain pulse and DC voltage to common sustain electrodes.
The plasma display panel is driven for a time frame that is divided into a reset period, an address period, and a sustain period. During the reset period, a Ramp-up waveform is applied to all scan electrodes simultaneously. During the address period, a negative polarity scan pulse is sequentially applied to the scan electrodes. Simultaneously with the sequential application, a positive polarity data pulse is synchronized with the scan pulse, to thereby be applied to the address electrodes. Also, during the sustain period, a sustain pulse is applied alternately to the scan electrodes and the sustain electrodes.
In another implementation, the above described hybrid binder may be used in the dielectric layer 130 formed on the back substrate 110. Specifically, the white dielectric layer 130 is formed of a parent glass, filler, and hybrid binder. In this case, the white dielectric layer 130 and barrier ribs 140 can be baked together. Since the hybrid binder contains an organic binder with properties of an inorganic material, the strength of the barrier ribs 140 can be enhanced, and also, a bonding force between the barrier ribs 140 and the lower dielectric layer 130 can be enhanced.
First, as shown in
After completely forming the transparent electrodes 180a and 180b and bus electrodes 180a′ and 180b′, as shown in
Then, as shown in
After completing the formation of the protective layer 195, as shown in
Then, as shown in
The above described method is one example of a process for forming the lower dielectric layer using a screen printing method. Hereinafter, a process for forming the lower dielectric layer using a green sheet method will be described in brief. First, after coating a base film with a dielectric layer material, the resulting dielectric layer material is covered with a protective cover film, to prepare a green sheet. Then, the green sheet is laminated on a glass back substrate while removing the base film from the green sheet. By baking the laminated green sheet after removing the protective cover film, the lower dielectric layer is completed. The formation of the lower dielectric layer using the above described green sheet laminating method has several advantages of uniform layer thickness, superior surface flatness, simplified process, and high productivity, but has a disadvantage of expensive material costs.
The lower dielectric layer 130 formed by the above described method is adapted to reflect visible rays back-scattered from phosphor layers. As a result, the lower dielectric layer 130 can serve to increase the brightness of the plasma display panel and to prevent diffusion of atoms discharged from the address electrodes.
Subsequently, as shown in
First, a photosensitive barrier rib material 140a containing a hybrid binder is prepared. Here, the hybrid binder has a feature that it contains an acrylate-based binder prepared by the above described process and the acrylate-based binder is linked with an inorganic material. As other features of the hybrid binder, a refractive index difference between the inorganic material and the acrylate-based binder is 0.15 to 0.2, a refractive index of the hybrid binder is about 1.4 to 1.6, and the inorganic material is any one of SiO2, Al2O3, CaO, and TiO2. Also, the acrylate-based binder is 3-(Trimethoxysilyl) propyl methacrylate and/or 3-Glycidoxypropyltrimethoxysilane, and the hybrid binder has a BBO temperature of 450˜500° C.
Thereafter, as shown in
Thereafter, as shown in
As a result, since there is no organic material residue after completing the baking process, there are no problems of, for example, a deterioration in reflectivity caused by color tubidity of the barrier ribs, and consequently, a deterioration in brightness and color temperature, and out-gassing during a discharge. Also, since a hybrid binder contains an organic material with properties of an inorganic material, it can achieve the effect of improving the strength of the barrier ribs as compared to barrier ribs made of a conventional photosensitive barrier rib material. With the improved strength of the barrier ribs, also, a bonding force between the barrier ribs and the lower dielectric layer can be enhanced.
The above described lower dielectric layer material may be prepared to contain the hybrid binder included in the photosensitive barrier rib material. In the present implementation, although the above described barrier rib material contains the hybrid binder and can solve a refractive index problem represented by a conventional photosensitive barrier rib material, the lower dielectric layer material is not subjected to an exposure process and thus, is free from the refractive index problem. However, adding the hybrid binder to the lower dielectric material has the effect of increasing the strength of the lower dielectric layer material, similar to the barrier ribs.
As a binder to link a glass, etc. as a constituent material of the lower dielectric layer with an organic solvent, etc., a hybrid binder containing an acrylate-based binder can be used. In this case, similarly, to link an inorganic material with the binder, the inorganic material is synthesized with hydroxyl ions (OH−) using a negative ion polymerization. Then, by adding the acrylate-based binder into the inorganic material synthesized by the negative ion polymerization, the hybrid binder can be prepared. In this case, as described above, the acrylate-based binder may have a high molecular weight functional group attached to a side chain. Also, as described above, 3-(Trimethoxysilyl) propyl methacrylate or 3-Glycidoxypropyltrimethoxysilane can be used as the binder.
The hybrid binder synthesized by the above described process has a BBO temperature of 450˜550° C. Therefore, the dielectric layer material and the barrier rib material can be baked together.
With the above described baking process, only a part of the hybrid binder linked with the inorganic material remains. Specifically, since the organic and inorganic materials contained in the binder define a network, the organic material is not completely removed. More specifically, the barrier rib contains 0.1˜0.2% of an organic material component. In turn, the organic material component contains 0.01˜0.06% of the acrylate-based binder.
Then, as shown in
As shown, the barrier ribs 140 have a shape similar to a trapezoid, and the phosphor layers 150a, 150b, and 150c can be sufficiently coated onto side surfaces of the barrier ribs 140. Accordingly, as compared to the conventional barrier ribs and phosphor layers coated thereto as shown in
As shown in
Hereinafter, a process for sealing the upper and lower panels will be described in detail. The sealing process is performed using a screen printing method, dispensing method, or the like. In the screen printing method, after a patterned screen is located above a substrate with a predetermined distance therebetween, a paste required to form a sealing material is squeezed and transferred, so as to print a desired shape of sealing material. The screen printing method has advantages of simplified production facility and high material use efficiency.
In the dispensing method, a thick-layer forming paste is directly discharged onto a substrate using an air pressure according to CAD wiring data used in the manufacture of a screen mask, to form a sealing material. The dispensing method has advantages of reducing mask manufacturing costs and achieving a great freedom in the formation of a thick layer.
As shown, a sealing material 600 is coated on the front substrate 170 or the back substrate 110. Specifically, the sealing material 600 is printed or coated using a dispensing method at a position spaced apart from the outline of the substrate by a predetermined distance.
Subsequently, the sealing material 600 is subjected to a baking process. During the baking process, the organic material contained in the sealing material 600 is removed, and the front substrate 170 and the back substrate 110 are bonded with each other. Also, with the baking process, the sealing material 600 can be increased in width and decreased in height. In the present implementation, although the sealing material 600 is printed or coated, a sealing tape may be attached to the front substrate or the back substrate.
Then, an aging process can be performed to improve, for example, characteristics of the protective layer under a predetermined temperature condition.
Additionally, a front filter can be formed on the front substrate. The front filter includes an electromagnetic interference (EMI) shielding layer to prevent electromagnetic waves from being emitted from the panel to the outside. The EMI shielding layer may be formed by patterning a conductive material to have a specific pattern, in order to achieve a desired visible ray transmission required in a display device while shielding the electromagnetic waves. The front filter can be formed with a near-infrared shielding layer, a color compensating layer, an anti-reflection layer, etc.
It will be apparent that various modifications and variations can be made.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2007-0027184 | Mar 2007 | KR | national |
