Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2001-08-10
2003-10-14
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C313S586000
Reexamination Certificate
active
06632116
ABSTRACT:
BACKGROUND OF THE INVENTION
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-033932, filed Feb. 12, 1999; No. 11-318127, filed Nov. 9, 1999; and No. 11-319687, filed Nov. 10, 1999, the entire contents of all of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a plasma display panel, and to the method and apparatus for manufacturing the plasma display panel. In particular, the present invention relates to a plasma display panel which is provided with barrier ribs for partitioning the discharge region of the plasma display panel, and to the method and apparatus for manufacturing such a plasma display panel.
2. Description of the Related Art
Conventionally, a CRT has been extensively employed as an image display device. However, the CRT is defective in the respects that it is large in overall size and weight, and that it requires a high voltage. Under the circumstances, a flat type image display device such as a light emitting diode (LED), a liquid crystal display device (LCD), a plasma display panel (PDP), a plasma addressed liquid crystal display (PALC), etc. has been developed in recent years, and these devices are now increasingly utilized.
Among them, due to the propagation of multimedia, the plasma display panel which is adapted to be employed as an interface of information in a color display device of large image area is now noticed as promising because the structure thereof where the emission of plasma is utilized is simple, it is suited for achieving a large image area and an excellent image quality, it is light in weight, and it is thin-walled so that it is free from restriction regarding the installation place thereof.
This plasma display panel comprises discharge display cells having minute spaces which are encircled by barrier ribs partitioning a space formed between a pair of flat insulating substrates, wherein each of the discharge display cells is provided therein with a pair of discharge electrodes and an address electrode which is disposed at the bottom of the discharge display cell. The minute spaces of the discharge display cells are formed of an air-tight structure filled therein with a dischargeable gas such as a rare gas, thereby enabling a plasma to be generated in the spaces through the discharging between the discharge electrodes and the address electrode, wherein the switching of light emission of the discharge display cells is effected by the address electrode.
The plasma can be generated by selectively applying a voltage between facing discharge electrodes, and vacuum ultraviolet rays released from the plasma are utilized for generating light from the phosphors formed within the discharge display cells, thereby making it possible to utilize the discharge display cells as the light-emitting elements of image display device.
Therefore, it is required, for the performing the aforementioned switching, to apply a voltage between the discharge electrodes. However, if the electrostatic capacity of the discharge display cell is large, the driving current between the discharge electrodes is rendered to be increased. As a result, the power consumption of the plasma display panel is required to be increased, thereby raising a problem that the power source equipment of the plasma display panel is required to be enlarged.
Further, although the plasma display panel constructed as described above is simple in structure, and suited for enhancing the fineness of image, each of the electrodes and phosphors disposed inside the discharge display cells is permitted to be exposed directly to the plasma being generated. As a result, due to the sputtering effect of the plasma, the surfaces of these electrodes and phosphors are deteriorated, thereby raising a problem that the light emission efficiency of the display panel is liable to be decreased.
With a view to overcome these problems, there has been proposed a plasma display panel wherein a dielectric layer is formed on the opposing electrodes disposed inside the discharge display cell to thereby protect the surface of each electrode with this dielectric layer, thereby making it possible to reduce the electrostatic capacity of the discharge display cell and to prevent the electrodes and phosphors from being deteriorated by the plasma generated (Jpn. Pat. Appln. KOKAI No. H8-77930; and Jpn. Pat. Appln. KOKAI No. H7-57630).
As for the method of forming a dielectric layer of uniform thickness on the address electrodes of discharge display cell, there is generally known a method wherein a dielectric paste is printed, and the uniformity of thickness and the flatness of the printed layer are enabled to be achieved through the leveling effect of the surface of printed paste.
However, even if a dielectric paste of low fluidity is employed, with a view to ensure a uniform thickness and flatness of a dielectric layer, for forming a dielectric layer having a thickness of about 5 &mgr;m on an electrode pattern ordinarily having a thickness of about 10 &mgr;m, the surface of the dielectric layer to be obtained would become wavy due to the recessed and projected surface constituted by regions where the electrode pattern is existed and regions where the electrode pattern is not existed, thereby making it difficult to obtain a dielectric layer which is uniform in thickness.
On the other hand, if a dielectric paste having a high leveling property, i.e. excellent in fluidity is employed with a view to ensure the flatness of dielectric layer, it would become difficult to secure a sufficient thickness of the dielectric layer as it is formed on the address electrode, thereby possibly permitting part of the address electrode to be exposed to the outside. Thus, the thickness of the dielectric layer would become non-uniform, thus making it very difficult to obtain a dielectric layer which is uniform in thickness and excellent in flatness.
Therefore, since the thickness or flatness of the dielectric layer formed on the surface of address electrode becomes non-uniform as mentioned above, the quantity of electric charge to be stored in the dielectric layer is caused to differ depending on the regions thereof. As a result, a voltage for controlling the emission of light is caused to differ for each of the discharge display cells depending on the location thereof, thereby raising a problem that it is impossible for the address electrode disposed between the barrier ribs to display a stable and accurate light emission.
Furthermore, the forming of the dielectric layer by means of printing method leads to an increase in number of steps by one additional step in the manufacture of the back plate of plasma display panel. Furthermore, since the material for forming the barrier rib differs from the material for forming the dielectric layer, there is a room for improvement not only in terms of productivity but also in terms of material cost.
There has been also proposed, as a method of forming the barrier rib integral with the dielectric layer, a press molding method wherein the material for forming the barrier rib is press-molded by making use of an intaglio having a pattern of the barrier ribs. Although it is required, in this case, to control the thickness of the dielectric layer through the adjustment of gap between the intaglio and the substrate, the provision of the gap makes it difficult to obtain a sufficient pressing pressure, and still more, it is difficult to precisely fit the barrier rib-forming material into the aforementioned intaglio of barrier rib-like configuration.
Additionally, the provision, in advance, of the thickness-wise configuration of the dielectric layer in the intaglio is difficult in the aspect of working the intaglio. Further, if there is a wavy portion in thickness-wise in the glass substrate or any non-uniformity in the pressing pressure to the intaglio, it becomes difficult to make constant the gap between the intaglio and the substrate, thus failing to obtain the dielectric layer having a uniform thickne
Akimoto Yasumasa
Arai Junichi
Kato Isao
Minato Takao
Nakamura Ryuichi
Ramsey Kenneth J.
Toppan Printing Co. Ltd.
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