Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
1999-09-21
2002-11-12
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S585000, C313S586000, C345S060000, C345S041000
Reexamination Certificate
active
06479932
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to an AC plasma display panel (AC-PDP) for use in a flat panel television set and in a flat panel display unit, more in detail to the AC-PDP which realizes a high emission efficiency and improves display drive performance.
(b) Description of the Related Art
A color plasma display excites a fluorescent substance to make an emission display by means of a ultraviolet ray generated by gas discharge, and an application of the display panel to a large-screen television set is expected. Various systems have been developed for the color PDPs among which a reflection-type AC coplanar switching plasma display panel (AC-IPS-PDP) is excellent in its brightness and ease of manufacture.
FIGS. 1A
to
1
C show a typical reflection-type ACIPS-IPS-PDP.
FIG.1A
is an elevational view partially in section of a rear substrate,
FIG. 1B
is a side sectional view of a front substrate and
FIG. 1C
is a horizontal sectional view of the rear substrate.
A front substrate
100
disposed at a display side has a plurality of stripe transparent electrodes
13
and a plurality of narrow bus electrodes
14
extending in parallel on a glass substrate
11
. An indium-tin oxide thin film or a tin oxide thin film is employed as the transparent electrode
13
which results in a large resistance of the transparent electrode
13
. For compensating the large resistance of the transparent electrode
13
, the bus electrode
14
is made from a good conductor metal such as silver in the form of a thick film, copper, aluminum and chromium in the form of a thin film to provide a high discharge current for sufficient emission in a large display unit. A dielectric layer
18
and a protection layer
19
are formed on the transparent electrode
13
and the bus electrode
14
. The dielectric layer
18
may be formed as a transparent insulation layer having a thickness of about 20 to 40 micrometers by applying low melting point glass paste to the glass substrate
11
and sintering the glass substrate
11
at a high temperature slightly below 600° C. The protection layer
19
is formed by, for example, vacuum-evaporation of a magnesium oxide to form a thin film having a large secondary electron radiation coefficient and an excellent anti-sputtering ability.
After stripe data electrodes
16
are formed on a glass substrate
12
, a dielectric layer
21
including low-melting point glass as a main component is formed. After stripe partition walls
17
are formed, powdery fluorescent substances
20
of red, green and blue are sequentially applied on a bottom surface and a side surface of a trench formed by the partition walls
17
to complete a rear substrate
200
. The partition walls
17
not only secure a discharge space but also prevent cross-talk of the discharge and seepage of a luminous color, and ordinarily have a width of 30 to 100 micrometers and a height of 60 to 200 micrometers. After the rear substrate
200
and the front substrate
100
are coupled and the periphery of the both substrates is sealed with frit glass, a panel is completed by heating the substrates, exhausting an inner gas and finally enclosing a discharge gas having a rare gas as a main component therein.
A pair of the transparent electrodes
13
are separated by a discharge gap
23
. One of the transparent electrodes acts as a scanning electrode
31
and the other acts as a maintaining electrode
32
, and various voltage waveforms are applied to the two transparent electrodes and the data electrode for driving.
A simple example of a basic driving of the electrodes is shown in FIG.
2
. Data pulses having a polarity reverse to the polarity of scanning pulses are applied to the data electrode
16
depending on display data of the scanning electrode in the cell in timing with the scanning pulses having a negative polarity sequentially applied to the selected scanning electrode
31
Thereby, a counter discharge occurs between the scanning electrode
31
and the data electrode
16
The counter discharge as a trigger generates a surface discharge between the maintaining electrode
32
and the scanning electrode
31
to complete a write operation. The write discharge generates a wall charge on the surfaces of the maintaining electrode
32
and the scanning electrode
31
. While the maintaining discharge for the surface discharge is generated by the maintaining pulse applied between the maintaining electrode
32
and the scanning electrode
31
during a maintaining period in the cell in which the wall charge is formed, the maintaining discharge is not generated in the cell in which the write operation is not conducted even if a maintaining pulse is applied because electric fields generated by the wall charges are not superimposed. The application of the desired number of the maintaining pulses generates a specified emission display. Gray scale display can be realized by repeating the write operation and the maintaining discharge operation every sub-field. A preliminary discharge operation in which compulsory discharge is conducted by applying high voltages to all cells may be employed before the write operation as shown in
FIG. 2
for elevating performance of the write operation. Although the driving system of separating the scanning emission and the maintaining emission is illustrated in
FIG. 2
, various driving systems have been proposed including a system in which the scanning pulse and the maintaining pulse are combined.
JP-A-8(1996)-315735 or JP-A-8(1996)-250029 describes a prior art of the PDP.
FIG. 3
shows another conventional AC plasma display panel having a coupling part
15
, and
FIG. 4
shows a conventional electrode structure.
In order to employ the AC color plasma display in a wide range of use such as in a television for home use in the prior art, a display driving performance may be, however, reduced even when an improved structure is employed for elevating an emission efficiency.
With increase of resolution and the number of display gray scales, an accurate write operation in a short period of time is required, a writing on one scanning electrode
31
in a full-color panel having 480 scanning electrodes is required to be performed in 3micro-seconds, and a write operation in a higher resolution panel such as that in a high precision television is required to be performed in 2 micro-seconds. However, in the conventional electrode structure, a position of starting counter discharge at a time of the write operation between the data electrode
16
and the scanning electrode
32
and a position of strong discharge are scattered on a whole part formed by overlapping between the scanning electrode
31
and the data electrode
16
. Accordingly, the write condition does not become uniform to make a flicker, or to generate write inferiority on the entire panel in an extreme case only to perform impractical display. High electricity consumption also becomes obvious.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide an AC-PDP which realizes an emission display having high brightness and reduction of power dissipation by improving an emission efficiency.
Another object is to provide an AC-PDP in which a write operation can be securely conducted in a short period of time and has low power dissipation by devising a data electrode shape.
The present invention provides, in a first aspect thereof, an AC plasma display panel including: first and second glass substrates; a plurality of partition walls sandwiched between said first glass substrate and said second glass substrate, said partition walls extending in a column direction to separate a plurality of discharge cells in a row direction; a pair of transparent electrodes for extending in said row direction parallel to each other with a discharge gap therebetween in each of said discharge cells to operate surface discharge (in-plane discharge) therebetween; a plurality of metallic bus electrodes each disposed on said first glass substrate corresponding to each of said transp
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