Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2000-10-24
2002-08-13
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C313S584000, C445S024000, C445S025000
Reexamination Certificate
active
06433489
ABSTRACT:
TECHNICAL FIELD
This invention relates to a plasma display panel, and a manufacturing method for the same.
BACKGROUND ART
Large screen display devices with high picture quality, such as that produced by high definition television (HDTV), have recently become the focus of much expectation. As a result, research and development of display devices such as cathode ray tubes (CRTs), liquid crystal displays (LCDs), and plasma display panels (PDPs) is taking place. These various types of display devices each have the following characteristics.
CRTs have excellent resolution and picture quality, and are widely used in conventional televisions and the like. The large increases in depth and weight required to produce a large screen CRT, however, are problematic, and solving this difficulty is crucial for the development of such CRTs. Due to this problem, it is believed to be difficult to produce a CRT with a large screen of more than 40 inches.
LCDs, on the other hand, use less electricity than CRTs, and are extremely light and slim. Nowadays, LCDs are being increasingly used as computer monitors. However, the structure of a typical LCD, which uses a thin film transistor (TFT) screen or similar, is extremely intricate, and this means that manufacture of such a device requires a plurality of complicated processes. As a result, manufacturing yield decreases as screen size is increased. This means that it is currently considered difficult to manufacture an LCD with a screen of more than 20 inches.
In contrast to CRTs and LCDs, PDPs have the advantage of being able to realize a lightweight display with a large screen, and in addition employ a driving method in which the PDP itself emits light to produce a screen display. As a result, in the current search for the next generation of displays, research and development of large screen PDPs is being pursued particularly aggressively, and products with screens of more than 50 inches are being developed.
In a PDP, a glass substrate, on which a plurality of pairs of display electrodes and a plurality of barrier ribs are arranged in a stripe formation, is placed in opposition to another glass substrate. Phosphors in each of the three colors red, green and blue are applied to the spaces between the barrier ribs. The two glass substrates are then sealed together so as to be airtight, and a discharge gas enclosed in the discharge space between the barrier ribs and the two glass substrates. Discharge is produced by ultraviolet light generated by the discharge gas, thereby causing the phosphors to emit light. PDPs such as this one can be divided into two types, direct current (DC) and alternating current (AC), according to the driving method used. AC PDPs are thought to be more suitable for producing a large screen device, and thus are the most common type of PDP.
However, current specifications for HDTV include a 1920×1080 pixel array, and a dot pitch of 0.16 mm×0.48 mm for 42-inch class screens. Consequently, the area occupied by one cell is as little as 0.077 mm
2
, which is seven to eight times smaller than the size specified by the NTSC (National Television System Committee) standard for televisions in the same 42-inch class, and the number of scanning lines is almost three times as great as that specified in the NTSC standard. For these reasons, the manufacturing processes required to produce PDPs for HDTV use are of higher precision than those required to produce a television complying with the NTSC standard.
Consequently, the plurality of pairs of display electrodes in a PDP have to be set at intervals smaller than those in televisions compliant with the NTSC standard.
However, this creates certain problems when manufacturing the PDP. The plurality of pairs of electrodes are generally manufactured using a method disclosed in Japanese Laid-Open Patent 9-35628. The actual procedure for manufacturing electrodes using such a method is as follows. First, a transparent conductive film formed from indium tin oxide (ITO) or tin oxide (SnO
2
), and a metal conductive film formed from three layers of chromium, copper and chromium (Cr—Cu—Cr) are successively formed on the surface of a front glass substrate using sputtering or a similar method. Following this, photolithography is used to process the conductive film so that the electrodes have a uniform shape. Photolithography is performed by repeating processes in which a photoresist is applied, and patterning and etching performed. Consequently, a large number of process steps are used, and the operation tends to take a long time. Furthermore, unwanted erosion caused by the etching solution, and slipping of the mask used for patterning are more likely to occur as the processes are repeated, making it difficult to preserve the same level of precision throughout the entire procedure. These problems are a particular obstacle when manufacturing the intricately-formed plurality of pairs of display electrodes used for HDTV.
There is still a great deal of room for improvement in current PDP manufacturing methods with regard to the technical problem of how to manufacture a plurality of pairs of display electrodes in a way that is faster and more precise than conventional methods.
DISCLOSURE OF THE INVENTION
The present invention was developed with the aim of solving the above problem. The object of the invention is to provide a PDP manufacturing method that incorporates laser ablation processing into the process used to manufacture the plurality of display electrodes and the like, thereby rationalizing the manufacturing process by shortening the time required, and manufacturing a PDP with a high yield.
The above object may be realized by a plasma display panel manufacturing method including a display electrode forming step of forming a plurality of pairs of display electrodes in parallel lines on a main surface of a first plate, and a plate sealing step of aligning the main surface of the first plate with a main surface of a second plate, and sealing the first and second plates together. Here, the plurality of pairs of display electrodes are formed in the display electrode forming step by coating the main surface of the first plate with display electrode material, and performing laser ablation on parts of the display electrode material. Remaining parts of the display electrode material form the display electrodes.
To be more specific, in the display electrode forming step, the display electrode material may contain transparent electrode material and metal electrode material, and the plurality of pairs of display electrodes may be formed using the following method. First, the main surface of the first plate is coated with the transparent electrode material, and laser ablation performed on the transparent electrode material to form transparent electrode parts. Then, at least surfaces of the transparent electrode parts are coated with the metal electrode material to form metal electrode parts that are in electrical contact with the transparent electrode parts.
Furthermore, in the display electrode forming step, the plurality of pairs of display electrodes may be formed in the following way. Laser ablation is performed on the transparent electrode material to form transparent electrode parts and alignment marks. Then, at least surfaces of the transparent electrode parts are coated with metal electrode material to form metal electrode parts, the alignment marks being used to align the metal electrode material with the transparent electrode parts.
If a plurality of pairs of display electrodes are manufactured in this way, laser processing can be performed simply by performing a laser ablation process, and then washing and drying processes. Therefore, the plurality of pairs of display electrodes can be formed more quickly and using a fraction of the number of processes required by a conventional photolithography method or the like. This reduces the generation of environmentally harmful waste solutions and the like, so that the use of the laser ablation process is likely to resolve various environmental probl
Aoki Masaki
Funami Koji
Hibino Junichi
Hujiwara Shinya
Inoue Isamu
Philogene Haissa
Price and Gess
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