Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-12-20
2004-06-01
Awad, Amr (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S067000, C345S063000, C345S066000, C315S169400
Reexamination Certificate
active
06744413
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel used for a flat television set, an information display or the like, and a plasma display apparatus having the same. More particularly, the invention relates to an AC in-plane discharge plasma display panel capable of providing high-definition and bright displaying, and a plasma display apparatus having the same.
2. Description of the Related Art
The plasma display apparatus is designed to perform displaying by using ultraviolet rays generated by gas discharge to excite a phosphor to emit a light, and expected to be applied to a large-screen television set, an information display or the like. A variety of systems have been developed for a color plasma display apparatus, and an AC in-plane discharge plasma display is advantageous because of its luminance, easy panel manufacturing, and so on.
FIG. 1
is a schematic view showing the structure of a typical AC in-plane discharge color plasma display panel of a reflection type.
FIG. 2A
is a schematic view showing a positional relation among a scanning electrode, a maintenance electrode and a bus electrode in the conventional color plasma display panel.
FIG. 2B
is a schematic view showing a positional relation between a partition wall and a data electrode in the conventional color plasma display panel.
In a front substrate
100
as a display side substrate, a plurality of strip transparent electrode films
3
and narrow strip bus electrodes
4
are formed in parallel as in-plane discharge electrodes on a glass substrate
1
. For the transparent electrode film
3
, an ITO thin film or a tin oxide thin film can be used. To supply a sufficient discharge current for the light emission of a large-area panel, however, the electrical resistances of these thin films are too large. Accordingly, the metallic bus electrode
4
having high electrical conductivity is provided. For such a bus electrode
4
, an electrode made of, for example, a thick silver film or a metallic thin film containing copper, aluminum, chromium or the like may be used. A dielectric layer
7
is formed over the bus electrodes
4
. In general, the dielectric layer
7
is formed in the following manner. That is, first, low melting point glass paste is coated on the transparent electrode film
3
having the bus electrode
4
formed, and by baking this film at a high temperature, a transparent glass layer having a thickness of about 20 to 40 &mgr;m and high withstand voltage is formed. Then, a magnesium oxide thin film having a high secondary electron emission coefficient and a high sputtering resistance is formed as a surface protective layer on the glass layer.
On the other hand, in a backside substrate
200
disposed in parallel with the front substrate
100
, a plurality of strip data electrodes
5
and a dielectric layer
10
covering these data electrodes
5
are formed on a glass substrate
2
. A main component contained in the dielectric layer
10
is low melting point glass. On the dielectric layer
10
, a belt-like partition wall
6
is formed to be extended in a vertical direction (columnar direction). The partition wall
6
is a structure having a width set in a range of about 30 to 120 &mgr;m, and a height set in a range of about 80 to 150 &mgr;m. This structure is generally made of a mixture of oxide powder such as alumina or the like, and low melting point glass. On the bottom portions and the side faces of a plurality of grooves defined by the partition walls
6
, phosphor layers
9
each made of powdered phosphor to emit a red, green or blue light are coated. The colors of lights emitted from the phosphor layers
9
are arrayed in a horizontal direction (line direction) in the above order.
Then, the backside substrate
200
and the front substrate
100
are combined together, the peripheries of both substrates are sealed with frit glass and, after the execution of heating and exhaustion, discharge gas containing rare gas as a main component is sealed therein. In this way, the color plasma display panel is constructed.
The partition wall
6
serves to secure discharge space, and prevent crosstalk and the color blotting of an emitted light during discharging.
In the front substrate
100
, in-plane discharge electrodes make a pair sandwiching an in-plane discharge gap
11
. That is, one is an in-plane discharge electrode (scanning electrode)
13
, and the other is an in-plane discharge electrode (maintenance electrode)
14
. Then, the conventional color plasma display panel is driven for displaying by applying various voltage waveforms to three kinds of electrodes, i.e., the electrodes
13
and
14
, and the data electrode
5
provided in the backside substrate
200
.
FIG. 3
is a timing chart showing a driving waveform applied to each electrode when the scanning electrode of the n-th line is designed as Sn, the maintenance electrode is designed as Cn, and the data electrode is designed as Dj.
Scanning pulses are sequentially applied to the scanning electrodes Sn, Sn+1, Sn+2, Sn+3, and so on. In matching with this timing, a data pulse having polarity reverse to that of the scanning pulse is applied to the data electrode Dj according to the display data of a display cell on each of the scanning electrodes. Accordingly, inter-plane discharging occurs between each of the scanning electrodes Sn, . . . and so on, and the data electrode Dj. By a writing operation performed based on such inter-plane discharging, positive wall charges are generated on the surface of each of the scanning electrodes Sn, . . . and so on. In the display cell having the wall charges generated, subsequently, in-plane discharging occurs by a maintenance pulse applied between the maintenance electrodes Cm (Cn, Cn+1, . . . and so on) and each of the scanning electrodes Sn, and so on.
On the other hand, in a display cell having no wall charges generated and no writing performed therein because of the application of no data pulses and the occurrence of no discharging between the data electrode and the scanning electrode, no maintenance discharging occurs even when a maintenance pulse is applied. This is because of the lack of an electric field superposition effect provided by wall charges.
Then, light emission and displaying are carried out by applying the maintenance pulse to the display cell having the wall charges generated by a specified number of times.
For the maintenance electrode Cm, it is not necessary to apply a pulse selected for each piece unlike the case of the scanning pulse. Thus, the respective maintenance electrodes Cm are connected in common and, as shown in
FIG. 3
, the same voltage waveform is applied thereto. In addition, in a practically used panel, in order to improve the operability of writing, a preparation sequence has been employed for the purpose of Activation inside the display cell and the generation of proper wall charges, which is achieved by applying high voltages to all the display cells prior to a writing operation, and executing a preparation discharging operation for forcible discharging, or the like.
A sub-field method has been employed for the gradational displaying of the AC plasma display. This is due to the fact that in the AC plasma display, the voltage modulation of emitted light displaying luminance is difficult, and the number of light emission times must be changed for luminance modulation. The sub-field method is designed to reproduce a multilevel image by breaking down the multilevel image into a plurality of binary display images and executing continuous displaying at a high speed so as to obtain a visual integration effect.
Such a conventional in-plane discharge AC plasma display has an excellent characteristic. However, as can be understood from the structure of the in-plane discharge electrode shown in
FIG. 1
, two in-plane discharge electrodes making a pair are necessary for the light emission of one display line. An in-plane discharge gap between such in-plane discharge electrodes is relatively narrow, i.e.,
Awad Amr
McGinn & Gibb PLLC
NEC Corporation
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