Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
1999-01-19
2001-12-25
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C315S169400, C345S060000
Reexamination Certificate
active
06333599
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a plasma display system employing a plasma display panel (hereinafter referred to as “PDP”).
In recent years, a plasma display system employing an AC surface-discharge PDP is expected as a promising large-sized, thin-profile color display system. The structure of the AC surface-discharge PDP will be described below. Most of the PDPs of this type are of a three-electrode structure. Two base plates, a front glass base plate and a rear glass base plate, are arranged opposite to each other with a specific gap put therebetween. A plurality of pairs of line electrodes are formed on the inner surface (opposite to the rear glass base plate) serving as a display screen, of the front glass base plate. The line electrodes are covered with a dielectric substance. A plurality of column electrodes coated with phosphor are formed on the rear glass base plate. The column electrodes may be covered with a dielectric substance. The intersection portion of one pair of the line electrodes and one column electrode, as seen from the display screen side, constitutes one discharge cell. A space between both the base plates is filled with a discharge gas (typically, a mixed gas of two kinds or more of He, Ne, Xe, Ar and the like). The discharge gas causes discharge when a voltage pulse is applied between the electrodes, and ultraviolet light generated from the excited discharge gas is converted into visible light by the phosphor. For the color display, a set of three kinds of cells generally form one pixel. The line electrodes which perform sustaining of discharge for main light emission, are called the electrodes for sustaining discharge.
The realization of a large-sized display by employing such a PDP increases the amount of a current to be supplied to the electrodes, giving rise to a problem in increasing the power consumption. To reduce the power consumption, it is effective to improve the efficiency of luminescence during discharge in the PDP.
When dimensions of each cell are reduced to increase definition of the display image, that is, to increase the number of pixels, a loss in energy for producing plasma is increased, which causes a problem of lowering the efficiency of luminescence.
Techniques for improving the efficiency of luminescence are already known. For example, Japanese Patent Laid-open Nos. Hei 8-22772 and Hei 3-187125 disclose a technique in which the size and shape of each electrode for sustaining discharge are designed to improve the efficiency of luminescence. Japanese Patent Laid-open Nos. Hei 7-262930 and Hei 8-315734 disclose a technique in which the material of a dielectric substance covering each electrode for sustaining discharge is designed to improve the efficiency of luminescence.
SUMMARY OF THE INVENTION
The above-described prior art techniques for improving the efficiency of luminescence in the AC surface-discharge PDP did not take into account time variation of the efficiency of luminescence in a discharge period of time.
The present invention has been made on the discovery of time variation of the efficiency of luminescence in which a time of the maximum efficiency of luminescence lags behind a time of the maximum discharge current in the prior art PDP, and accordingly, an object of the present invention is to provide a plasma display system employing a plasma display panel in which the discharge current before the time at which the maximum discharge current appears in the prior art PDP is reduced for making the time variation of the discharge current conform to the time variation of the efficiency of luminescence.
The features of the present invention to achieve the above object are as follows:
(1) A plasma display system having a plasma display panel comprising a pair of base plates for forming a plurality of discharge cells therebetween, and a plurality of pairs of electrodes for sustaining discharge to form plasma through a dielectric substance thereon in the plurality of discharge cells, the plurality of pairs of electrodes for sustaining discharge being disposed on a same one of the pair of base plates, wherein the plasma display panel is configured such that a discharge current integrated over 40% of a discharge time Td from a start of the discharge time Td is smaller than a discharge current integrated over a remainder of the discharge time Td in one discharge, the discharge time Td being defined as a time interval over which a discharge current does not drop to less than 5% of its maximum value in one discharge.
(2) A plasma display system having a plasma display panel comprising a pair of base plates for forming a plurality of discharge cells therebetween, and a plurality of pairs of electrodes for sustaining discharge to form plasma through a dielectric substance thereon in the plurality of discharge cells, the plurality of pairs of electrodes for sustaining discharge being disposed on a same one of the pair of base plates, wherein the plasma display panel is configured such that a discharge current and an efficiency of luminescence become maximum, respectively, after 40% of a discharge time Td from a start of the discharge time Td, the discharge time Td being defined as a time interval over which a discharge current does not drop to less than 5% of its maximum value in one discharge.
(3) A plasma display system having a plasma display panel comprising a pair of base plates for forming a plurality of discharge cells therebetween, and a plurality of pairs of electrodes for sustaining discharge to form plasma through a dielectric substance thereon in the plurality of discharge cells, the plurality of pairs of electrodes for sustaining discharge being disposed on a same one of the pair of base plates, wherein, assuming that in each of the pair of electrodes for sustaining discharge, a portion which extends from an end of the electrode on a discharge gap side thereof in a direction where the electrode is opposed to the other one of said pair of electrodes and which has a length equivalent to two-thirds of the width of the electrode is taken as a primary part and the remaining portion is taken as a secondary part, a portion of at least one of the pair of electrodes, positioned in each discharge cell, is specified such that a ratio of an area of the primary part to an area of the secondary part is smaller than 1.4 and a side surface of the secondary part in a direction perpendicular to the direction in which the pair of electrodes are opposed to each other is close to a boundary between said discharge cells.
(4) A plasma display system described in (3), wherein the ratio of the area of the primary part to the area of the secondary part is smaller than 1.
(5) A plasma display system having a plasma display panel in which pairs of electrodes for sustaining discharge to form plasma through a dielectric substance in a plurality of discharge cells each of which at least has a separation wall in one direction are provided on a same base plate, wherein, assuming that in each of the pair of electrodes for sustaining discharge, a portion which extends from an end of the electrode on a discharge gap side thereof in a direction where the electrode is opposed to the other one of the pair of electrodes and which has a length equivalent to two-thirds of the width of the electrode is taken as a primary part and the remaining portion is taken as a secondary part, a portion of at least one of the pair of electrodes, positioned in each discharge cell, is specified such that a ratio of an area of the primary part to an area of the secondary part is smaller than 1.4 and a side surface of the secondary part in a direction perpendicular to the direction in which the pair of electrodes are opposed to each other is close to the separation wall.
(6) A plasma display system described in (5), wherein the ratio of the area of the primary part to the area of the secondary part is smaller than 1.
(7) A plasma display system described in (5), wherein a partial separation wall is provided between adjacent ones of the discharge cells
Ho Shirun
Ishigaki Masaji
Kawai Michifumi
Kawanami Yoshimi
Murase Tomohiko
Day Michael H.
Gerike Matthew J.
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
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