Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
1999-02-25
2002-12-17
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S491000
Reexamination Certificate
active
06495957
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to Japanese application No. HEI 10(1998)-287424 filed on Oct. 9, 1998, whose priority is claimed under 35 USC §119, the disclosure of which is incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel (PDP) of a surface-discharge type and a display device using the same.
PDPs have become widely used for television monitors, video monitors for computers and the like since color display became practical with PDPs. For further spread of the PDPs, structures suitable for high definition are being developed.
2. Description of Related Art
Three-electrode AC surface-discharge PDPs are commercialized as color display devices. Here, the surface-discharge structure means a structure in which a first main electrode and a second main electrode are arranged in parallel on an inner surface of one of paired substrates (referred to as a first substrate). The first and second main electrodes serve as a positive electrode and a negative electrode alternately in AC drive for sustaining a light-emitting state by use of wall charge. With this structure, fluorescent layers for color display can be disposed on a second substrate opposed to the first substrate having the main electrodes disposed thereon, thereby to be kept at a distance from the main electrodes. Thereby, the deterioration of the fluorescent layers due to ion impact at electric discharges can be reduced for longer life of PDPs. Since the main electrodes extend in the same direction as row electrodes defining rows of a screen, the surface-discharge PDPs need third electrodes (column electrodes) for selecting cells on the rows and barrier ribs for partitioning a discharge space for every column. The main electrodes are each in the shape of a linear belt extending along the full width of the screen. As regards arrangement of the barrier ribs, a stripe pattern in which the barrier ribs are arranged in the shape of linear belts in plan view is superior from the view point of productivity to a mesh pattern in which the barrier ribs separates the cells individually.
In a typical configuration of the three-electrode structure, a pair of main electrodes is arranged on every row of the screen. The distance between the two main electrodes of each row (referred to as a surface-discharge gap) is set about several tens of microns so that discharges are generated by application of a voltage of about 150 to 200 volts. On the other hand, the distance between the main electrodes on adjacent rows (referred to as a reverse slit) is set sufficiently larger than (about several times as large as) the surface-discharge gap in order to prevent unnecessary discharges across the rows and reduce electrostatic capacity. In other words, the interval between the main electrodes on a row is different from that between the main electrodes on adjacent rows. With this typical configuration, since the reverse gap does not contribute to light emission, the use of the screen is limited and is disadvantageous in brightness. Also, it is different to realize higher definition through reduction of a pitch between rows (row pitch).
There is conventionally proposed a technique wherein an arrangement of electrodes is adopted wherein N+1 main electrodes (N is the number of rows) are equidistantly disposed and two adjacent rows serve as an electrode pair for generating a surface discharge (illustrated in Japanese Unexamined Patent Publication No. HEI 2(1990)-220330) and a frame is divided into an odd-numbered field and an even-numbered field which are time-sequentially displayed (Japanese Unexamined Patent Publication No. HEI 9(1997)-160525). In this arrangement of electrodes, each main electrode except the ones on both ends makes electrode pairs with the main electrodes on both sides thereof in the direction of arrangement. That is, the main electrode is used for displaying both the odd-numbered fields and the even-numbered fields. The main electrodes on the ends each form an electrode pair with the main electrode on one side in the direction of arrangement. Only odd-numbered rows are used for displaying the odd-numbered field and only even-number rows are used for displaying the even-numbered field. For example, for sustaining the light-emitting state in the odd-number field, voltages of the same phase are applied to the main electrodes defining rows which are not used for display in this field (in this case, even-numbered rows). Thereby interference of discharges between the odd-numbered rows and the even-numbered rows can be reduced without need to provide barrier ribs between the rows.
With the above-described setting of the phrase of drive voltages, although unnecessary surface discharges can be prevented on the rows not used for display, discharges on the rows used for display expand toward adjacent rows, i.e., the rows not used for display. Accordingly, resolution in the direction of the columns (vertical resolution) is impaired.
SUMMARY OF THE INVENTION
An object of the present invention is to prevent the expansion of discharges in the column direction to improve the resolution.
The present invention provides a plasma display panel comprising a plurality of row electrodes defining rows of a screen, the row electrodes being arranged at intervals so that adjacent row electrodes are capable of serving as an electrode pair for generating a surface discharge, wherein each of the row electrodes includes a belt-shaped base extending along the full length of the screen in a direction of the rows and protrusions extending from the base toward an adjacent row electrode in every column.
In the present invention, the plan-view shape of the main electrodes disposed equidistantly is the shape of linear belts of constant width having partial cut-offs in such a manner that all cells have an equal electrode area. Since an electric field is not generated at a cut-off portion, the discharge produced on one side of the main electrode can be prevented from expanding to the other side thereof. Because the area of the electrode decreases by the area of the cutoff, discharge current decreases, so that a drive circuit is less burdened. Decline in brightness with the decrease of the discharge current can be compensated by raising the frequency of drive voltage for sustaining light emission.
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Katayama Takashi
Kurogi Seiki
Nakahara Hiroyuki
Ukai Yoshitaka
Yoshida Kenji
Berck Ken A
Fujitsu Limited
Patel Vip
Staas & Halsey , LLP
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