Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
2000-10-03
2003-05-06
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S491000, C313S587000, C313S112000, C313S503000, C313S581000
Reexamination Certificate
active
06559592
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a display device and a method for manufacturing the same, and more particularly, to a display device with color filters used as electrodes which improves the color purity and optical efficiency of the display device and a method for manufacturing the same.
2. Description of the Background Art
Flat-panel display devices are generally classified into liquid crystal displays (LCD), field emission displays (FED), plasma display panels (PDP), and electroluminescence (EL).
Among those flat-panel display devices, the plasma display panel (PDP) being actively studied recently has a simple structure, is simply manufactured, has a higher brightness and luminous efficiency as compared to other flat-panel display devices, and can have an additional memory function. In addition, the PDP can implement a large-sized screen of more than 40 inches having a wide field angle of more than 160°. Therefore, the PDP having the above advantages has a potential of driving the flat-panel display market in the future.
When ultraviolet rays generated by gas, e.g., He—Ne or Ne—Xe, during plasma discharge within a discharge cell partitioned by partition walls excite red, green, and blue fluorescent materials formed on the partition walls, visible light generated when the excited fluorescent materials are transited to the ground state is emitted. Using this principle, the PDP displays characters and graphics by means of the emitted visible light. Meanwhile, the PDP is classified into an alternating current PDP (AC-PDP) and a direct current PDP (DC-PDP), said AC-PDP will now be described in more detail.
FIG. 1
is a structural diagram of the AC-PDP illustrating one cell in a general alternating plasma display panel (AC-PDP). The AC-PDP includes a front glass substrate
1
for displaying images, a back glass substrate
23
arranged in parallel to the front glass substrate
1
at a certain distance from the front glass substrate
1
, and partition walls
13
positioned between the front glass substrate
10
and the back glass substrate
23
for forming a discharge space in the discharge cell in order to keep the distance between the front and back glass substrates constant and shut off electrical/optical interference between cells.
Here, the front glass substrate
1
further includes: an upper dielectric layer
3
for accumulating wall charges, keeping the discharge voltage, and protecting electrodes from ion bombardment and preventing the diffusion of ions during gas discharge; and a protective layer
9
formed on the surface of the upper dielectric layer
3
for protecting the upper dielectric layer
3
from sputtered plasma particles to thereby lengthen the life span thereof, increasing the relatively high efficiency of the emission of secondary electrons when a low ion energy is bumped against the surface during plasma discharge, and reducing the amount of changes in the discharge characteristics of refractory metals by means of oxides. At this time, the protective layer
9
is mainly made of magnesium oxide (MgO).
In addition, the upper dielectric layer
3
includes a sustain electrode
5
, a transparent electrode, made of Indium Tin Oxide (ITO) and a bus electrode
7
made of metal which is connected with the sustain electrode
5
.
The back glass substrate
23
includes an address electrode
19
for occurring discharge of the sustain electrode
5
and the bus electrode
7
, an under layer
21
for attaching the address electrode
19
and the back glass substrate
23
, a lower dielectric layer
17
for covering the address electrode
19
, and a fluorescent material
15
for covering the lower dielectric layer
17
and the partition walls
13
formed thereon and generating visible light.
In addition, a black top
11
for absorbing light incident from the outside through the front glass substrate
1
is connected to the upper portion of the wall partition
13
.
In the thusly constructed PDP, a discharge is initiated between the address electrode
19
and the sustain electrode
5
, in a state that the inner space of the discharge cell is filled with a discharge gas, for example, a gas mixture of He—Ne and Ne—Xe. When the discharge is continuously maintained between the sustain electrodes
5
, vacuum ultraviolet (VUV) rays with a wavelength of 147 mm are emitted. Then, the vacuum ultraviolet rays excite the fluorescent material
15
. When the fluorescent material
15
is transited from the excited state to the ground state, red, green, and blue visible light is emitted and accordingly desired images are displayed through the front glass substrate
1
.
Among the flat-panel display devices, the electroluminescence (EL) are active display devices using the phenomenon that the fluorescent material becomes luminescent by applying an electric field to a conductive fluorescent material coated on a glass substrate or a transparent organic film, which are divided into thin film electroluminescent devices (TFEL), dispersion type electroluminescent devices (EL), and solid state displays (SSD) which are fabricated by improving the thin film electroluminescent devices, said solid state display will now be described in more detail.
FIG. 2
is a structural diagram of a general solid state display, in which a back glass substrate
31
, a back electrode
32
formed on the back glass substrate
31
, a thick film dielectric layer
33
formed on the back glass electrode
32
for preventing dielectric breakdown, a fluorescent layer
35
formed on the thick dielectric layer
33
for generating visible rays, a thin film dielectric layer
36
formed on the fluorescent layer
35
, and a transparent electrode
37
formed on the thin film dielectric layer
33
are stacked one after another. In addition, a planarization layer
34
for planing the interface between the thick film dielectric layer
33
and the fluorescent layer
35
is further stacked between the thick film dielectric layer
33
and the fluorescent layer
35
.
The driving principle of the thusly constructed SSD will now be described in brief.
Firstly, when a predetermined voltage (e.g., 22 V) is applied to the back electrode
32
and the transparent electrode
37
, electrons are emitted at the interface level of the thick film dielectric layer
33
and the thin film dielectric layer
36
adjacent to the fluorescent layer
35
by means of a tunneling effect. The emitted electrons are accelerated by a high electric field (e.g., 10
6
V/m) to turn into thermal electrons. The thermal electrons collide with atoms contained in the fluorescent material (e.g., ZnS:Mn) and as a result these atoms become excited. The excited atoms emit visible rays while transiting to the ground state. By this principle, the solid state display displays desired images.
Furthermore, the thick film dielectric layer
33
serves to prevent dielectric breakdown and diffusion between the back electrode
32
and the fluorescent layer
35
, stably supply a high voltage, and keep the solid state display's thermal stability.
The PDP and SSD cited among the flat-panel display devices implement all kinds of colors by emitting the corresponding light from red, green, and blue fluorescent materials contained in each cell of the PDP and SSD. However, there occurs a problem that the color purity is reduced due to the phenomenon that colors emitted from the fluorescent materials are mixed with one another. To solve the above problem, color filters are attached on the front glass substrate, said color filters emit the respective colors corresponding to the fluorescent materials for thereby increasing the color purity.
However, in order to increase the color purity, the color filters attached on the front glass substrate of the PDP and SSD still have a problem of decreasing the brightness of the light emitted from the PDP and SSD, as compared to the brightness of the light emitted from the PDP and SSD having no color filter attached on the front glass substrate.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the pre
Fleshner & Kim LLP
LG Electronics Inc.
Patel Ashok
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