1. Field of the Invention
The present invention relates to a printing screen and a printing process using the same. More particularly, the present invention relates to a method for improving a side-bottom ratio of a fluorescent layer in a plasma display panel and the printing screen used.
2. Description of Related Art
In recent years, with the rapid advancement of microelectronics technology, the information, communication, network technology and the relative industry have also developed. With that trend, the display apparatus, showing words, data, pictures and moving images, has become an indispensable element. Wherein, the plasma display apparatus, with its advantages such as big size, self-luminescence, wide view angle, thinness and full colors, has a great potential of becoming the mainstream flat panel display apparatus in its next generation.
Following the preceding paragraph, the fluorescent layer 21 is disposed over the side wall of the rib 30 and over the dielectric layer 17. When the drive voltage is provided by the X, Y electrodes and the address electrode 15, the discharge gas in the discharge chambers 13 will be transformed into plasma and emit ultraviolet. When the fluorescent layer 21 is irradiated by the ultraviolet, it will emit visible light, whereby the plasma display panel 100 displays images. It can be learned from the foregoing that the thickness and the coating area of the fluorescent layer 21 over the side wall of the rib 30 and over the dielectric layer 17 have great impact on the luminescent efficiency of the plasma display panel 100.
As shown in
In
Accordingly, the present invention is directed to a printing screen capable of enhancing even thickness of the fluorescent layer during a printing process.
The present invention is also directed to a printing process capable of forming a fluorescent layer with more even thickness.
The present invention is also directed to a method for improving a side-bottom ratio so that a fluorescent layer in a discharge chamber has more even thickness and accordingly, the plasma display apparatus can have better luminescent efficiency.
According to an embodiment of the present invention, a printing screen adapted for a printing process of a fluorescent layer in a plasma display panel is provided. The printing screen comprises a plurality of printing units, and each of the printing units comprises a body and a protrusion structure. Wherein, each body has an ink aperture. The protrusion structure extends from a surface of the body into the ink aperture.
According to one embodiment of the present invention, each protrusion structure of each printing unit comprises a first protrusion and a second protrusion, wherein the ink apertures can be of a quadrangular shape. In each of the printing units, the first protrusion and the second protrusion are respectively connected to two neighboring side edges of the quadrangular ink aperture. In another embodiment, the first protrusion and the second protrusion are respectively connected to two opposite side edges of the quadrangular ink aperture. In addition, the shape of the ink apertures can also be rectangular and the aforementioned opposite side edges can be the two short sides of the rectangular ink aperture. Wherein, the positions of the first protrusion and the second protrusion of each printing unit can be symmetric. In another embodiment, the positions of the first protrusion and the second protrusion can be asymmetric.
According to one embodiment of the present invention, the protrusion structure of each printing unit comprises a plurality of first protrusion and a plurality of second protrusion, wherein the ink aperture can be of a quadrangular shape. In each of the printing units, the first protrusions and the second protrusions are respectively connected to two neighboring side edges of the quadrangular ink aperture. In another embodiment, the first protrusions and the second protrusions are respectively connected to two opposite side edges of the quadrangular ink aperture. Additionally, the ink aperture can be of a rectangular shape, and the said opposite side edges can be the two short sides of the rectangular ink aperture. Wherein, in each printing unit, the positions of the first protrusions and the second protrusions in each printing unit are symmetric. In another embodiment, the positions of the first protrusions and the second protrusions can be asymmetric. Additionally, in each printing unit, an area ratio of the protrusions to the ink aperture can be between 0.056:1 to 0.120:1.
According to an embodiment of the present invention, a printing process utilizing the said printing screen and a plurality of chambers is disclosed. The printing screen is disposed over the chambers with the ink apertures aligned with the chambers. And then the ink liquid is coated on the printing screen while the ink liquid flows into the chambers through the ink apertures. In each of the chambers, a temporary gap is formed between a portion of the ink liquid and the side wall of the chamber, wherein the gap is under the protrusion.
According to one embodiment of the present invention, a method for improving a side-bottom ratio is provided. The method is adapted for improving the side-bottom ratio of a fluorescent layer in a plasma display panel, wherein the plasma display panel comprises a plurality of discharge chambers besieged by a rib. The method for improving a side-bottom ratio starts by providing the aforementioned printing screen. Next, the printing screen is disposed over the rib with the ink apertures aligned with the discharge chambers. And then a fluorescent material is applied onto the printing screen when the fluorescent material flows into the discharge chambers through the ink apertures. In each of the discharge chambers, a temporary gap is formed between a portion of the fluorescent material and the side wall of the discharge chamber, wherein the gap is under the protrusion. Next, a drying process is performed whereby the fluorescent layer is formed on the bottom and the side wall of each discharge chamber. Wherein, the side-bottom ratio of the film thickness of the fluorescent layer in each discharge chamber can be between 1:2 to 2:1, and more preferably, the side-bottom ratio can be 1:1.
According to one embodiment of this invention, the drying process for the fluorescent material comprises a baking process.
To sum up, the present invention, the printing screen, the printing process and the method for improving side-bottom ratio, can be applied in a printing process of the fluorescent layer in a plasma display panel to improve the side-bottom ratio of the fluorescent layer in the discharge chamber and then eventually enhance the luminescent efficiency of the plasma display apparatus.
Various specific embodiments of the present invention are disclosed below, illustrating examples of various possible implementations of the concepts of the present invention. The following description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
The present invention provides a printing screen with protrusions in the ink apertures. The printing screen with protrusions enables the ink liquids to flow in different speeds to the same ink aperture. Therefore, the gas in the discharge chambers can be emitted from where the ink liquid flows in a slower speed, so as to avoid the uneven thickness of the fluorescent layer due to the gas enveloped in the ink liquids in the discharge chamber.
In one embodiment of the present invention, each of the protrusion structure 414 of each printing unit 410 comprises a first protrusion 413 and a second protrusion 415. As shown in
Furthermore, the positions of the first protrusion 413 and the second protrusion 415 can be symmetric (as shown in
It should be noted that the said protrusion structure 414 not only comprise a single first protrusion 413 and/or a single second protrusion 415, but also comprise a plurality of first protrusions 413 and/or a plurality of second protrusions 415. For instance, with reference to
The positions of the said first protrusions 413 and/or the second protrusions 415 can be symmetric or asymmetric. However, in order not to affect the amount of the ink liquid flowing through the ink aperture 416, it is preferred that the positions of the first protrusions 413 and the second protrusions 415 are asymmetric (as shown in
Please refer to
It should be noted that the dimensions of the ink aperture 416 and the protrusion structure 414 shown in
The following example is a printing process for a fluorescent layer in a plasma display panel using the aforementioned printing screen. Additionally, it should be obvious from the foregoing embodiment that the printing screen of the present invention can be of various designs. Although the following embodiment takes the printing screen 400 as an example, other embodiments of the printing screen in the present invention can also be applied in the following statement, and are not limited to the printing screen shown in
As shown in
And then the fluorescent material 502 is coated onto the printing screen 400 when the fluorescent material 502 flows in the discharge chamber 13 through the ink apertures 416. A scraper 504 is usually used in coating the fluorescent material 502 onto the printing screen 400.
It should be noted that partial area of the ink aperture 416 is occupied by the protrusion structure 414 of the printing screen 400. Therefore, while the fluorescent material 502 flows into the discharge chamber 13 through the ink aperture 416, the fluorescent material 502 first flows into the areas where the protrusion structure 414 is not disposed. And then a temporary gap 512 is formed in a portion of the discharge chamber 13 under the protrusion structure 414. Therefore, gas 510 in the bottom of the discharge chamber 13 can be emitted through the gap 512 (as shown in
Please refer to
According to the experiment data of the present invention, the thickness of the fluorescent layer 506 on the side wall of the discharge chamber 13 is thinner than that of the conventional apparatus. For instance, in one embodiment of the present invention, the thickness of the fluorescent layer formed on the side wall of the discharge chamber 13 when using the conventional printing screen 300 (as shown in
It should be noted that although the printing process for the fluorescent layer in a plasma display apparatus is cited as an example, the process can also be applied in other printing process, and not limited in the process of the present invention. It should be apparent to persons skilled in the art that the printing screen of the present invention can be applied in other printing processes and achieve the same effect of the aforementioned embodiments.
To sum up, the present invention has the following advantages:
1. In the present invention, the printing screen, the printing process and the method for improving side-bottom ratio, a temporary gap is formed in a portion of the discharge chamber under the protrusions when the ink liquid flows into the discharge chamber through the ink apertures. Therefore, the gas on the bottom of the chamber can be squeezed out by the ink liquid and is emitted outside the chamber through the gap while the ink liquid flows into the bottom of the chamber. Eventually, the uneven thickness due to the gas enveloped by the ink liquid can be reduced.
2. In the present invention, the printing screen, the printing process and the method for improving side-bottom ratio, the printing screen can be applied in the printing process of the fluorescent layer in the plasma display panel to improve the side-bottom ratio of the fluorescent layer in the discharge chamber. Hence, the luminescent efficiency of the plasma display apparatus can be promoted.
The above description provides a full and complete description of the embodiments of the present invention. Various modifications, alternate construction, and equivalent may be made by those skilled in the art without changing the scope or spirit of the invention. Accordingly, the above description and illustrations should not be construed as limiting the scope of the invention which is defined by the following claims.
Number | Name | Date | Kind |
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7045944 | Ushifusa et al. | May 2006 | B2 |
Number | Date | Country | |
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20060113884 A1 | Jun 2006 | US |