Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
1998-08-28
2001-12-11
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S587000
Reexamination Certificate
active
06329751
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel in which a fluorescent layer emits light to form an image by receiving ultraviolet light generated during gas discharge.
2. Description of the Related Art
A plasma display panel has been widely known as a flat type display panel, equivalent in quality to a cathode ray tube, due to its capacity to display large amounts of data, it's a wide viewing angle, and superior brightness and contrast features.
In general, the plasma display panel is divided into a DC plasma display panel and an AC plasma display panel according to its operation principle. The DC plasma display panel has all electrodes exposed to a discharge space in which charges move directly between opposite electrodes. While, in the AC plasma display panel, at least one electrode is coated with a dielectric and discharge is generated by the electric field of wall-charges.
Also, the plasma display panel is divided into an opposed discharge type and a surface discharge type according to the composition of electrodes. In the opposed discharge type plasma display panel, an address electrode and a scanning electrode are installed at each unit pixel to face each other and an addressing discharge for selectively discharging a desired pixel and a sustaining discharge for sustaining the addressing discharge are generated between the two opposed electrodes.
In the surface discharge type plasma display panel, however, each unit pixel is provided by a scanning electrode and a common electrode opposing an address electrode. Addressing and sustaining discharges are generated between the address electrode and the scanning electrode, and the scanning electrode and the common electrode, respectively.
Ultraviolet light generated during discharge in the plasma display panel allows a fluorescent layer disposed in a discharge space to emit light, so that an image is formed.
FIG. 1
shows an example of a conventional plasma display panel.
As shown in the drawing, the conventional plasma display panel includes a substrate
10
, a first electrode
11
formed on the substrate
10
, a dielectric layer
12
coated over the first electrode
11
and the substrate
10
, a partition
13
formed on the dielectric layer
12
for defining a discharge cell and preventing cross talk between the discharge cells, and a fluorescent layer
14
formed in a predetermined pattern inside the discharge space between the partitions
13
.
A transparent front substrate
20
is installed atop the partition
13
. Second and third electrodes
21
and
22
are formed on the lower surface of the front substrate
20
to be perpendicular to the direction of the first electrode
11
. A dielectric layer
23
and a protective layer
24
are coated in sequence on the lower surfaces of the second and third electrodes
21
and
22
and the front substrate
20
.
As a predetermined voltage is applied to each electrode, charges are accumulated in the dielectric layer
12
. The accumulated charges trigger a discharge between the first and second electrodes
11
and
21
so that charged particles are formed on the lower surface of the dielectric layer
23
of the front substrate
16
. When a predetermined voltage is applied to the second and third electrodes
21
and
22
in such a state, a sustaining discharge is generated. Thus, a plasma is formed in a charged gas layer in the discharge space. In the plasma, ultraviolet light is emitted and the fluorescent layer
14
excited by the ultraviolet light emits light.
During the operation of the plasma display panel as above, part of the ultraviolet light emitted by the gas discharge is absorbed by the front substrate
20
and the partition
13
where the fluorescent layer
14
is not formed. Also, part of the light emitted by the fluorescent layer
14
is dissipated into the dielectric layer
12
and the substrate
10
under the fluorescent layer
14
, which does not affect brightness.
Plasma display panels introduced to solve the above problems are disclosed in U.S. Pat. No. 5,182,489 and Japanese Patent No. hey 5-80390.
FIG. 2
shows an example of a plasma display panel described in the above documents. Here, the same reference numerals as those in
FIG. 1
indicate the same members. As shown in the drawing, a visual-ray reflection layer
16
having an upper surface processed with an insulation material is formed between a substrate
10
and a dielectric layer
12
. The reflection layer
16
reflects the light proceeding toward the substrate
10
from a phosphor layer
14
, toward a front substrate
20
, to thus increase brightness. However, since the reflection layer
16
reflects only the visual ray emitted by the phosphor layer
14
and has a limit in reflecting ultraviolet light generated during gas discharge, a considerable improvement in the brightness cannot be expected. In particular, since the transmittance of the visual light of the phosphor layer
14
is extremely low, there is a limit to improving the brightness using the reflection layer
16
.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a plasma display panel having a reflection film for reflecting light rays that would be lost during the first light emission toward a fluorescent layer to be used in the second light emission in a discharge space.
Accordingly, to achieve the above objective, there is provided a plasma display panel including front and rear substrates coupled to face each other, a partition formed between the front and rear substrates to define a discharge space, a discharger for generating parent light rays by discharging gas filled in the discharge space, a fluorescent layer, formed in a predetermined pattern in the discharge space, for emitting light by being excited by the parent light rays, and a reflection film, formed in an area where the fluorescent layer is not formed in the discharge space, for reflecting the parent light rays toward the fluorescent layer.
In the present invention, it is preferable that the reflection film is formed by superimposing at least two transparent thin film layers different from each other.
Also, it is preferable that the thin film layer is formed of material including salt of groups
1
A and
2
A of the periodic table and that the thin film layer is formed of at least one material selected from the group consisting of MgO, LiF, MgF
2
, CaF
2
, SrF
2
, and BaF
2
.
Further, it is preferable that thickness of the thin film layer is set to &lgr;/4n±&lgr;/16 and &lgr; is the wavelength of the parent rays.
REFERENCES:
patent: 4224553 (1980-09-01), Hellwig
patent: 4803402 (1989-02-01), Raber et al.
patent: 4827186 (1989-05-01), Knauer et al.
patent: 5182489 (1993-01-01), Sano
patent: 5780174 (1998-07-01), Tokito et al.
patent: 6008580 (1999-12-01), Nakamura et al.
patent: 35 27 884 (1986-02-01), None
patent: 0 284 138 (1988-09-01), None
patent: 4-332430 (1992-11-01), None
patent: 5-80390 (1993-11-01), None
Guharay Karabi
Lowe Hauptman & Gilman & Berner LLP
Patel Nimeshkumar D.
Samsung Display Devices Co. Ltd.
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