Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
1999-01-25
2002-07-16
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S584000, C313S583000
Reexamination Certificate
active
06420830
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel (hereinafter, called “PDP”) and more particularly to a PDP for minimizing the number of electrodes involving discharge in a discharge structure that pixels are formed at intersections of multiple electrodes, thereby improving luminance and resolution.
2. Description of Related Art
Typically, a PDP is a flat display device for displaying a dynamic or still picture using internal gas discharge phenomenon. According to the number of electrodes that are assigned to each pixel, the PDP is classified into a two-electrode type, a three-electrode type, and a four-electrode type. As for the two-electrode type, voltage for addressing and sustain is applied to two electrodes together. The three-electrode type is usually called a surface-discharge type. In the three-electrode type, switching or sustain is carried out by voltage applied to electrodes located on the sides of a discharge cell.
As a representative of such conventional PDP, the three-electrode surface-discharge PDP is illustrated in
FIGS. 1 through 3
.
FIG. 1
is an exploded, perspective view of the panel.
FIG. 2
is a cross sectional view of a pixel.
FIG. 3
shows disposition of electrodes. For helping readers to easily understand a discharge principal, an upper substrate is rotated at an angle of 90° in FIG.
2
.
As shown in the drawings, the conventional three-electrode surface-discharge PDP includes front substrate
1
for displaying image and rear-substrate
2
forming a rear side that are spaced apart and arranged in parallel with each other.
On the front substrate
1
are formed discharge sustain electrodes (hereinafter, one is called a “common electrode (C)” and the other is called a “scan electrode (S)”) paired in each pixel, for sustaining luminescence of a cell through mutual discharge therebetween. Each sustain electrode comprises transparent electrode
7
for preventing reduction of an aperture ratio and metal electrode
8
for reducing resistance of the transparent electrode
7
. Dielectric layer
5
is formed to limit discharge current of the two electrodes and insulate pairs of electrodes against one another. On the dielectric layer
5
is formed protective layer
6
.
The rear substrate
2
comprises: a plurality of walls
3
for partitioning a plurality of discharge spaces, namely, cells; a plurality of address electrodes A formed in parallel with the walls
3
, for generating vacuum ultraviolet by carrying out address discharge at intersections where the address electrodes A and the scan electrodes S cross; and a phosphor
4
formed on inner surfaces of the both walls
3
making up each discharge cell and on the surface of the rear substrate
2
, for producing visible rays for displaying images during the address discharge.
The following description concerns how a certain pixel emits light according to the conventional PDP having such configuration as described above.
Once a discharge start voltage is applied to a cell where the scan electrode S and the common electrode C are in a pair, surface discharge occurs between the two electrodes, so wall charge is accumulated on the inner surfaces of the corresponding discharge space.
Afterward, if an address discharge voltage is applied to the scan electrode S and a corresponding address electrode A, writing discharge occurs within the cell. Then, if a sustain discharge voltage is applied to the scan electrode S and the common electrode C, sustain discharge is caused by charged particles produced during the address discharge occurring between the address electrode A and the scan electrode S so that luminescence of the cell can be sustained during a certain period.
In other words, an electric field is formed within the cell by the discharge occurring between the electrodes. The electric field is formed when electrons in the discharge gas are accelerated and collide with neutrons. Collision of the electrons and neutrons causes the neutrons to be ionized at gently rising speed producing electrons and ions, and therefore, the discharge gas turns into plasma and vacuum ultraviolet are generated. The ultraviolet excites the phosphor
4
so as to generate visible rays. The visible rays are sent out through the front substrate
1
, so the luminescence of the corresponding cell, namely, image display can be recognized as viewed from the outside.
In such image display operation, a luminance characteristic and luminous efficacy depends on the amount of the visible rays that have been sent out. The amount of the visible rays sent out depends on various factors.
If the other factors including the luminous characteristic of the phosphor are the same, the amount of the visible rays depends on the aperture ratio of the pixel, namely, spacing between the metal electrodes
7
on the respective scan electrode S and common electrode C. As the spacing (aperture ratio) gets greater, the luminance characteristic and luminous efficacy gets better.
In such configuration of the conventional panel as described above, pixels are discriminated by the discharge sustain electrode group where the scan electrode S and the common electrode C are in a pair and the mutual discharge between the sustain electrodes disposed within the pixel is essentially required to sustain the luminescence.
Consequently, the spacing between the metal electrodes
8
is limited by the maximum spacing between the scan electrode S and the common electrode C disposed within the pixel, so there is a limit to improvement in the luminance characteristic and the luminous efficacy through increase of the aperture ratio, which corresponds to the spacing between the metal electrodes
8
, in the conventional art.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a plasma display panel that substantially obviates one or more of the limitations and disadvantages of the related art.
An objective of the present invention is to provide a plasma display panel (PDP) for allowing increase of an aperture ratio of a pixel by minimizing the number of discharge sustain electrodes disposed on a front substrate that is a surface on which images displayed outwardly, thereby improving a luminance characteristic of the PDP and improving resolution of the PDP through realization of high definition.
Additional features and advantages of the invention will be set forth in the following description, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure as illustrated in the written description and claims hereof, as well as the appended drawings.
To achieve these and other advantages, and in accordance with the purpose of the present invention as embodied and broadly described, a plasma display panel having two substrates coupled in parallel, each substrate comprising a plurality of electrodes, the respective electrodes on the two substrates crossing one another so as to form a plurality of pixels, the plasma display panel comprises: discharge sustain electrodes that one of the two substrates sustains discharge and that three electrodes are assigned per two pixels.
At least one of the assigned three discharge sustain electrodes comprises a transparent electrode and a metal electrode.
Two electrodes respectively located at each side among the three discharge sustain electrodes assigned per two pixels are metal electrodes.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 4190788 (1980-02-01), Yoshikawa et al.
patent: 4276492 (1981-06-01), Mayer
patent: 5369338 (1994-11-01), Kim
patent: 5578903 (1996-11-01), Pepi
patent: 5852347 (1998-12-01), Marcotte
patent: 5952782 (1999-09-01), Nanto et al.
patent: 5998935 (1999-12-01), Marcotte
patent: 6031329 (2000-02-01), Nagano
patent: 6072449 (2000-06-01
Fleshner & Kim LLP
Guharay Karabi
LG Electronics Inc.
Patel Nimeshkumar D.
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