Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-04-04
2002-10-22
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C345S206000, C345S212000
Reexamination Certificate
active
06469452
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel (PDP) and its driving method.
2. Description of Related Art
PDPs are display panels in which a pair of substrates formed with discharge electrodes thereon is disposed in an opposed relation and is sealed at the periphery to form a discharge space inside. The PDPs need a relatively high drive voltage for generating discharge. For this reason, they require a drive circuit (driver) with a high voltage resistance and a high capacity, and consequently, its production costs are high. Also, power consumption is large.
To cope with such problems, various countermeasures have been proposed. However, in the PDPs, the drive voltage cannot be decreased greatly because it is determined by discharge which is a physical phenomenon.
In the PDPs, the power consumption is the sum of power consumption required for charging inter-electrode capacity, power consumption required for discharge, and power consumption required by the drive circuit.
Among them, the power consumption required for charging the inter-electrode capacity is referred to as reactive power. A power collecting technique allows this power to be re-used to some extent for the purpose of reducing the power consumption. The power consumption required by the drive circuit is determined by the drive voltage. The power consumption required for discharge is represented by the drive voltage multiplied by electric current flowing into the discharge space by discharge. This is explained by taking an AC-driven PDP for example. First, a panel structure of the AC-driven PDP is described.
FIG. 44
is a perspective view partially illustrating the structure of a typical AC-driven three-electrode surface-discharge PDP. As shown in this figure, a PDP
10
is composed of a front panel assembly including a front substrate
11
and a rear panel assembly including a rear substrate
21
. The front substrate
11
and the rear substrate
21
are formed of glass.
Electrodes X and Y formed on an inside surface of the front substrate
11
are for generating a surface discharge for display between a pair of electrodes X and Y. The electrodes X and Y are each formed of a wide transparent electrode
12
of ITO, SnO
2
or the like and a narrow bus electrode
13
for reducing the resistance of the electrode. The bus electrode
13
is formed of a metal such as Ag, Au, Al, Cu, Cr, their laminate (e.g. a laminate of Cr/Cu/Cr) or the like. The electrodes X and Y are formed in a desired number to a desired thickness and width at desired intervals by utilizing a printing method for Ag and Au and by combining a film forming method such as vapor deposition, sputtering or the like with an etching method for other materials. Either the electrodes X or Y are used as scan electrodes.
A dielectric layer
17
is formed by applying a glass paste containing a low-melting glass frit, a binder and a solvent onto the front substrate
11
by a screen printing method, followed by burning.
On the dielectric layer
17
, a protective film
18
is mounted for protecting the dielectric layer
17
from damage owing to impact of ions generated by discharge at display operation. The protective film
18
is formed of MgO, CaO, SrO, BaO or the like, for example.
Address electrodes A are formed on an inside surface of the rear substrate
21
so as to cross the electrodes X and Y. The address electrodes A are for generating an address discharge where the address electrodes cross the scanning electrodes X or Y. The address electrodes A are formed of Ag, Au, Al, Cu, Cr, their laminate (e.g. a laminate of Cr/Cu/Cr) or the like, for example. The address electrodes A, like the electrodes X and Y, are formed in a desired number to a desired thickness and width at desired intervals by utilizing the printing method for Ag and Au and by combining a film forming method such as vapor deposition, sputtering or the like with the etching method for other materials.
A dielectric layer
24
is formed of the same material by the same method as the dielectric layer
17
.
Barrier ribs
29
can be formed on the dielectric layer
24
between the address electrodes by a sandblasting method, a printing method, a photo-etching method or the like. For example, they may be formed by applying a glass paste containing a low-melting glass frit, a binder, a solvent and the like onto the dielectric layer
24
, drying it, cutting it by the sandblasting method and burning. Alternatively, the barrier ribs
29
can be formed with use of a photo-conductive resin as the binder, which is exposed using a mask and developed, followed by burning.
Fluorescent layers
28
R,
28
G and
28
B can be formed by applying a phosphor paste containing a phosphor powder and a binder into grooves between the barrier ribs
29
by use of a screen printing method or a dispenser repeatedly for every color, followed by burning. Also, these fluorescent layers
28
R,
28
G and
28
B can be formed with use of sheet-form materials (so-called green sheets) for the fluorescent layers containing phosphor powders and a binder by a photolithographic method. In this case, a sheet of a desired color is attached over a display area on the substrate, exposed and developed. This process is repeated for every color, thereby forming the fluorescent layers of the respective colors in corresponding grooves between the barrier ribs.
The PDP
10
is produced by placing the above-described front and rear panel assemblies in the opposed relation so that the electrodes X and Y are orthogonal to the address electrodes, sealing the periphery and feeding a discharge gas of neon, xenon and the like into spaces surrounded by the barrier ribs
29
. In this PDP
10
, a discharge space at the crossing of one pair of electrodes X and Y and one address electrode is one cell region (unit light-emitting region) which is the minimum unit of display.
In this AC-driven PDP
10
, a discharge phenomenon across electrodes terminates spontaneously as a cell voltage (voltage applied to the discharge space) declines by the formation of a wall charge (an electric charge formed on a surface of the dielectric layer facing the discharge space). The amount of the wall charge formed at this time is an amount such that the cell voltage becomes a “0.” That is, with regard to the discharge across the electrodes X and Y, if +E (V) and 0 (V) are applied to the electrodes X and Y, respectively, the wall charge is so formed to have a potential of +E/2 (V) on the surface of the dielectric layer on the electrode.
If a capacity of C (F) is formed between the electrode and the surface of the dielectric layer on the electrode, a charge Qx=CE/2 (C) is formed on the surface of the dielectric layer above the electrode X and a charge Qy=−CE/2 (C) is formed on the surface of the dielectric layer above the electrode Y. Accordingly, if a drive frequency is f, a discharge current I can be represented by I=CE
2
f because the period of discharge is 2f. A power consumption P is P=CE
2
f because P=voltage×current. As understood from the above, a reduction in the voltage E and a reduction in the capacity C are necessary for reducing the power consumption at the discharge.
As measures to reduce the capacity C, the area of electrodes can be decreased, the thickness of the dielectric layer can be increased, the dielectric constant of the dielectric layer can be decreased and the like. However, a decrease in the area of electrodes and an increase in the thickness of the dielectric layer result in a rise in the drive voltage. As regards a decrease in the dielectric constant of the dielectric layer, it is necessary to develop a new dielectric having a low dielectric constant. Therefore, in order to reduce the power consumption at the discharge, the drive voltage needs to be decreased without a decrease in an electrode voltage.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide
Awamoto Kenji
Hashimoto Yasunobu
Otsuka Akihiro
Seo Yoshiho
Fujitsu Limited
Staas & Halsey , LLP
Tran Thuy Vinh
Wong Don
LandOfFree
Plasma display panel and its driving method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Plasma display panel and its driving method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Plasma display panel and its driving method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2997938