Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2000-10-30
2003-04-08
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S581000, C313S582000, C313S586000, C313S313000, C313S584000
Reexamination Certificate
active
06545412
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display device, and more particularly, to a plasma display device having a conductive strip or matrix for preventing occurrences of an electromagnetic wave.
2. Description of the Related Art
Plasma display devices utilize a gas discharge to form display images. The plasma display device has emerged as a flat panel display comparable to a cathode ray tube (CRT) in terms of picture quality since it exhibits excellent display properties such as display capacity, brightness, contrast, after-image, viewing angle, and the like. In plasma display devices, when an AC or DC voltage is applied to electrodes, a gas discharge is generated between the electrodes and the resulting radiation of ultraviolet light excites phosphors to emit light. Since the voltage required to generate a gas discharge is so high in plasma display devices, electromagnetic waves are generated, which may adversely affect humans.
FIG. 1
is an exploded perspective view showing the structure of a general AC-type plasma display device. Referring to
FIG. 1
, a first electrode
13
X, which is a common electrode, and a second electrode
13
Y, which is a scan electrode, are formed on the inner surface of a front glass substrate
11
, the two electrodes forming a pair. A third electrode
13
A, which is an address electrode, is formed on the inner surface of a rear glass substrate
12
. The first and second electrodes
13
X and
13
Y, and the third electrodes
13
A, respectively, are strips on the inner surface of the front and rear glass substrates
11
and
12
. When the substrates
11
and
12
are put together, the first and second electrodes
13
X and
13
Y, and the third electrodes
13
A cross each other perpendicularly. A dielectric layer
14
and a protective layer
15
are sequentially stacked on the inner surface of the front glass substrate
11
. Barrier walls
17
are formed on the top surface of a dielectric layer
14
′ which covers the rear glass substrate
12
, and cells
19
are defined by the barrier walls
17
. An inert gas such as argon fills the cells
19
. Further, each cell
19
is coated with phosphors
18
corresponding to red(R), green(G), or blue(B) pixels. Although not shown in
FIG. 1
, a bus electrode may be formed along the first and second electrodes
13
X and
13
Y.
The operation of a plasma display device having the above structure will now be described. First, a high voltage, which is called a trigger voltage, is applied to produce a gas discharge between the first and third electrodes
13
X and
13
A. Then, a discharge is created when positive ions are accumulated on the dielectric layers
14
and
14
′ by the trigger voltage. If the trigger voltage exceeds a threshold voltage, then argon gas within the cells
19
changes to a plasma state, and a stable discharge state can be maintained between the adjacent first and second electrodes
13
X and
13
Y. In the stable discharge state, ultraviolet light among discharge light bombards the phosphors
18
to produce light, which allows each pixel formed on a cell-by-cell basis to display an image.
The plasma display device described above generates electromagnetic waves when displaying an image. The harmful electromagnetic waves are emitted directly to users through the front surface of the display device. In order to prevent radiation of electromagnetic waves, usually a transparent conductive layer is formed on the surface of the front glass substrate
11
and grounded. However, the material used for transparent conductive layer is expensive and may degrade the brightness of the display device.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a plasma display device including an improved electromagnetic-wave shielding means.
It is another objective to provide a plasma display device having a means for improving the contrast as well as blocking electromagnetic waves.
Accordingly, to achieve the objectives, the invention provides a plasma display device including: front and rear substrates; strips comprised of a conductive material, which are formed on the front substrate, and an insulating layer formed so as to cover the conductive strips; first and second electrodes disposed parallel to each other on the insulating layer and a dielectric layer formed so as to cover the first and second electrodes; third electrodes formed perpendicular to the first and second electrodes on the rear substrate, and a dielectric layer formed over the interior surface of the rear substrate so as to cover the third electrodes; barrier walls which form discharge spaces on the dielectric layer of the rear substrate; and red, green, and blue phosphors coated between the barrier walls.
The conductive strips are extended along positions right above the barrier walls. The conductive strips are extended in parallel to the first and second electrodes in non light-emitting regions disposed between the pairs of first and second electrodes. Furthermore, The conductive strips are grounded. The conductive material is copper silver, indium tin oxide (ITO), or photosensitive silver paste. The conductive strips are formed by overlapping black strips disposed toward the outside of the front substrate and white strips disposed toward the inside of the front substrate.
The present invention also provides a plasma display device including: front and rear substrates; matrices comprised of a conductive material which are formed on the front substrate, and an insulating layer formed so as to cover the matrices; first and second electrodes formed parallel to each other on the insulating layer and a dielectric layer so as to cover the first and second electrodes; third electrodes formed perpendicular to the first and second electrodes on the rear substrate, and a dielectric layer formed over the interior surface of the rear substrate so as to cover the third electrodes; barrier walls which form discharge spaces on the dielectric layer of the rear substrate; and red, green, and blue phosphors coated between the barrier walls.
REFERENCES:
patent: 6008581 (1999-12-01), Ochiai et al.
patent: 6034474 (2000-03-01), Ueoka et al.
patent: 6078139 (2000-06-01), Ochiai et al.
patent: 6255778 (2001-07-01), Yoshikawa et al.
patent: 6429587 (2002-08-01), Sugimachi et al.
Harper Holly
Leydig , Voit & Mayer, Ltd.
Patel Nimeshkumar D.
Samsung SDI & Co., Ltd.
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