Electric lamp and discharge devices – With luminescent solid or liquid material – With gaseous discharge medium
Reexamination Certificate
2000-03-29
2003-06-10
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
With gaseous discharge medium
C313S582000, C313S587000
Reexamination Certificate
active
06577056
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flat panel display apparatus, and more particularly to a plasma display apparatus having a structure capable of improving a light efficiency.
2. Description of the Background Art
Recently, flat panel display apparatuses such as a liquid crystal display (LCD), a field emission display (FED) and a plasma display panel (PDP) are actively being developed. Especially, the PDP is the most remarkable owing to its advantages in that it is easily produced due to its simple structure, an excellence in the high luminance and a high light-emitting efficiency, a memory function, and a wide view angle more than 160° is obtained, and a large screen more than 40 inches can be implemented.
With reference to
FIG. 1
, the structure of a surface discharge AC PDP in accordance with a conventional art will now be described.
First, a front plate
10
and a back plate
20
are disposed facing each other spaced apart at a predetermined interval, between which discharge spaces
29
defined by barrier ribs
23
are formed.
A plurality of address electrodes
21
are formed in parallel in one direction on the upper surface of the back plate
20
, and the upper surface of the back plate
20
and the upper surface of the address electrodes
21
are covered by a dielectric layer
22
.
A plurality of barrier ribs
23
are formed on the upper surface of the dielectric layer
22
between the address electrodes
21
. The barrier ribs
23
serve to prevent the discharge spaces
29
prepared between each barrier rib from interfering electrically and optically. Black matrix bands
24
are formed on the upper surface of the barrier ribs
23
, to prevent a contrast degradation caused due to reflection of an external light.
A florescent layer
25
is coated on the both wall side of the barrier rib
23
and on the dielectric layer
22
covering the address electrode
21
.
On one side of the front plate
10
, a sustain/display electrode
11
and a scan electrode
12
are disposed spaced apart at a predetermined interval in the direction perpendicular to the direction of the address electrode
21
. As a material of the sustain/display electrode
11
and the scan electrode
12
, a translucent material, specifically, an indium tin oxide (ITO), is typically used so that luminescent light can pass through effectively.
Bus electrodes
13
are formed at the end portion of the sustain/display electrodes
11
and the scan electrodes
12
, so as to apply a stable driving voltage.
The bus electrode
13
is formed of an Al(aluminum) or Cr/Cu/Cr(chrome/copper/chrome) layer.
A dielectric layer
14
covers the sustain/display electrode
11
, the scan electrode
12
, the bus electrode
13
and the front plate
10
.
An MgO film
15
is coated on the surface of the dielectric layer
14
, as a protective film. The MgO protective film protects the PbO dielectric layer from a sputtering of ion. Also, when a low ion energy hits on the surfaced during plasma discharging of the PDP, due to its comparatively high second electronic generation coefficient characteristics, it renders the driving and sustain voltage of the discharge plasma to be lowered down.
The inside of the plasma display panel of
FIG. 1
, that is, the discharge cells (the discharge spaces
29
) surrounded by the barrier ribs are filled with He, Ne or Ar, or their mixed gas and a mixed gas of Xe.
FIG. 2
is a vertical sectional view of the surface discharge AC PDP taken along line of II—II of FIG.
1
. The same reference numerals of
FIGS. 1 and 2
represent the same elements, and thus, descriptions of
FIG. 2
are omitted.
Operational principle of the plasma display panel of the conventional art is as follows.
When a predetermined driving voltage is applied between the sustain/display electrode and the scan electrode, the plasma discharging occurs on the surface of the dielectric layer. Then, the ultraviolet ray generated from the plasma discharging excites the florescent material of a red color, (referred to as ‘R’, hereinafter), a green color (referred to as ‘G’, hereinafter) and a blue color (referred to as ‘B’, hereinafter) so as to be luminescent, and the visible ray of the R, G and B luminescent from the florescent material proceeds to the front plate through the dielectric layer and the display electrode, thereby displaying characters and graphic.
However, as to the plasma display panel of the conventional art has a problem in that the light luminescent from the florescent material is partially leaked through the back plate, degrading the light efficiency.
In an effort to solve the problem, there has been an attempt to heighten the light efficiency in a manner that the a material having a high reflectivity, that is, TiO
2
, is added in the dielectric layer so that the light luminescent in the discharge cell is directed to the front plate by being reflected on the dielectric layer without being penetrated through the back plate.
However, in spite of applying the method, the luminance of the light leaked through the back plate reaches 20% of the luminance of the light penetrated through the front plate, resulting in that the light efficiency of the plasma display panel is still low.
Light efficiency of the plasma display panel that has been recently developed is quite low, having approximately 1 Im/w, which is the biggest problem in view of commercial use of the plasma display panel. Therefore, the persons in the pertinent art try to find a method for improving light efficiency of the plasma display panel.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a plasma display apparatus which is capable of minimizing a loss of a back light through a back plate to thereby improve light efficiency.
To achieve these and other advantages and in accordance with the purposed of the present invention, as embodied and broadly described herein, there is provided a plasma display apparatus of which a back plate has a reflecting film on one side surface thereof.
In order to achieve the object, the reflecting film of the plasma display apparatus is a metal film.
In order to achieve the object, the metal film of the plasma display apparatus is made of one of aluminum, silver copper or chrome.
In order to achieve the object, the reflecting film of the plasma display apparatus is a metal film made by one of sputtering, evaporation, chemical vapor deposition, spin coating or a sol-gel method.
In order to achieve the object, the reflecting film of the plasma display apparatus is a mirror plane.
In order to achieve the object, the mirror plane is formed by using a silver mirror reaction.
In order to achieve the object, one side of a plate of the plasma display panel is flat, and the other side thereof forms a plurality of semicircular curves on which the reflecting film is formed.
In order to achieve the object, a flat plate micro lens is provided on the front surface of the reflecting film so as to condensing incident light.
In order to achieve the object, the plate micro lens is formed only at a portion corresponding to discharge cells between barrier ribs.
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Fleshner & Kim LLP
LG Electronics Inc.
Patel Ashok
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