Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
1999-10-15
2002-02-19
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S584000
Reexamination Certificate
active
06348762
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a color plasma display panel (a color PDP) used in a flat panel type television et, a display for displaying information, and the like, and more particularly to a color plasma display panel of a surface discharge type which has a superior white color characteristic and which can display a vivid color image.
BACKGROUND OF THE INVENTION
A plasma display is a display device which displays an image and so on by exciting fluorescent substance by using ultraviolet rays produced by gas discharge to emit light. The plasma display is expected to be applied to a large picture size television set, an information display, and the like.
Various types of color plasma displays have been developed. As typical types of the color plasma displays, there are a DC pulse memory type display and an AC memory type display. At present, the AC memory type is mainly used industrially because of the lifetime and the luminous efficiency. The AC memory type display is also categorized into an opposed electrode discharge type, a plane discharge type, and the like, depending on the cell structure, the electrode structure and so on. In particular, a reflection type AC surface discharge plasma display is superior in the luminance, easiness of panel fabrication, and the like.
FIGS. 16A through 16C
illustrate a panel structure of a typical reflection type AC surface discharge color plasma display.
FIG. 16A
is an elevational structural view in which a portion of a rear substrate
200
is cut away.
FIG. 16B
illustrates a structure at a cross section of a front substrate
100
.
FIG. 16C
illustrates a structure at a cross section of the rear substrate
200
.
The front substrate
100
which is on the side of a viewer comprises a glass substrate
1
and many band shaped transparent electrodes
3
formed in parallel on the glass substrate
1
, in a horizontal direction. On each of the transparent electrodes
3
, a bus electrode
4
is formed which bus electrode
4
is a band shaped narrow electrode to lower resistance of the transparent electrode
3
. The transparent electrodes
3
are formed of a thin film of ITO (Indium Tin Oxide) or tin oxide. However, the resistance of each transparent electrode
3
should be sufficiently small in order to conduct a discharge current sufficient to emit light in a large size panel, and, therefore, the bus electrode
4
made of metal having good conductivity is attached to each of the transparent electrodes
3
to lower the resistance thereof. The bus electrode
4
is made, for example, of a thick film of silver or a thin film of copper, aluminum, or chromium. On such structure including the transparent electrodes
3
and the bus electrodes
4
, a dielectric layer
7
and a protective layer
8
are formed. The dielectric layer
7
is fabricated by applying a low melting point glass paste on the structure including the electrodes
3
and
4
, and thereafter baking it at a temperature near 600 degrees Celsius. Thereby, the dielectric layer
7
is formed as a transparent insulating layer having a thickness of approximately 20 through 40 microns. The protective layer
8
is formed by vacuum evaporation and the like, and formed of a thin film of magnesium oxide (MgO) which has a large coefficient of secondary electron emission and has a superior anti-sputtering characteristic.
The rear substrate
200
comprises a glass substrate
2
on which band shaped data electrodes
5
are formed in a vertical direction and, thereafter, a dielectric layer
10
having low melting point glass as the basis is formed thereon. Thereafter, band shaped isolation walls
6
are formed in a vertical direction on the dielectric layer
10
. Then, at a bottom portion and side walls of each groove formed by the isolation walls
6
, powder type fluorescent substance
9
of red, green and blue colors are sequentially applied, and thereby the rear substrate
200
is completed. The isolation walls
6
secure discharge spaces, and serve to prevent cross talk of discharge and to prevent blotting of emitted light. Approximately, the isolation walls
6
are
30
through 100 microns in width and 80 through 200 microns in height.
The above-mentioned front substrate
100
and the rear substrate
200
are opposed to each other such that the protective layer
8
of the front substrate
100
is opposed to the isolation walls
6
of the rear substrate
200
. Both substrates
100
and
200
are then sealed at the periphery thereof by a fritted glass to obtain a panel assembly. The panel assembly is heated and evacuated, and discharge gas having rare gas as the basis thereof is introduced, thereby the plasma display panel is completed.
On the front substrate
100
, the transparent electrodes
3
with the bus electrodes
4
are disposed in pairs having a surface discharge gap
11
therebetween. One of the pair of transparent electrodes
3
with bus electrodes
4
is used as a scanning electrode
12
, and the other of the pair is used as a retaining or holding electrode
13
. Various voltage wave signals are applied to three kinds of electrodes, including the data electrodes
5
mentioned above, in addition to these scanning electrodes
12
and the retaining electrodes
13
, thereby the plasma display panel is driven to perform display operation.
FIG. 17
shows an example of waveforms of fundamental drive signals for the AC surface discharge type plasma display panel. Scanning pulses Sc
1
, Sc
2
,. . . , ScN are sequentially applied to the scanning electrodes
12
-
1
,
12
-
2
, . . . ,
12
-N. At the same timing as that of each of the scanning pulses Sc
1
, Sc
2
,. . . , ScN, a data pulse Dp is sequentially applied to each of the data electrodes
5
corresponding to a data to be displayed at each display cell. The data pulses have a polarity opposite to that of the scanning pulses. Thereby, a discharge, that is, an opposing electrode discharge, occurs between the scanning electrode
12
and the data electrode
5
opposing to each other. Also, the opposing electrode discharge triggers occurrence of the surface discharge between the retaining electrode
13
and the scanning electrode
12
, thereby writing operation is completed. Due to the surface discharge, i.e., a writing discharge, wall charges are produced on the surfaces over the scanning electrode
12
and the retaining electrode
13
. In a cell in which wall charges are formed, retaining discharge of the surface discharge, i.e., retaining surface discharge, occurs by retaining pulses Re applied between the retaining electrode
13
and the scanning electrode
12
. However, in a cell into which data is not written, retaining discharge does not occur even if the retaining pulses Re are applied, because there is no superimposing effect of electric fields caused by the wall charges. By applying the retaining pulses predetermined times, display of image and so on by light emission is performed.
Also, in order to improve write operation characteristic, a preliminary discharge operation is performed in which a high voltage is applied to all cells before performing write operation, so that any previously stored signals of the cells are erased and discharge is performed forcibly. In
FIG. 17
, Pd designates a preliminary discharge pulse, and Pe designates preliminary erasure discharge pulse.
As mentioned above, drive operation of a plasma display panel comprises a series of preparing operation, write operation and retained light emission operation. In
FIG. 17
, a series of such driving operation is shown as an example, in which driving operation of a plasma display panel is separated into a preparing interval in a whole panel, a write interval and a retaining interval. Various driving systems other than the above-mentioned system in which write operation and retain operation are separated can be used, for example, it is possible to use a system in which these operations are mixed. However, when considered in an individual display cell, it is common to these systems that, after preparing operation, write operation
Nunomura Keiji
Yanagida Kazuaki
Hutchins, Wheeler & Dittmar
NEC Corporation
Patel Vip
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