Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2000-06-29
2003-02-25
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S485000
Reexamination Certificate
active
06525469
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a full-color plasma display panel, and more particularly, to a full-color plasma display panel with a high color temperature that is achieved by adjusting the coverage of the phosphor materials within the plasma display panel.
2. Description of the Prior Art
A full-color plasma display panel (PDP) is composed of hundreds of thousands of tiny discharge cells arranged in a matrix formation. When a voltage is induced in one of these discharge cells, it causes a gas in the cell to discharge and generate ultra-violet radiation. This ultra-violet radiation falls on different phosphor materials and causes them respectively to emit one of three primary colors of light, i.e., red, green, or blue. Generally, the color of the emitted light depends on the composition of the phosphor materials. If the phosphor material is made of (Y,Gd)BO
3
, and Eu is added as a luminescent agent, the phosphor material will emit red light. If the phosphor material is made of Zn
2
SO
4
, and Mn is added as a luminescent agent, the phosphor material will emit green light. If the phosphor material is made of BaMgAl
14
O
23
, and Eu is added as a luminescent agent, the phosphor material will emit blue light. However, this blue light suffers from color degradation at higher temperatures. In order to improve the luminescence of the PDP, the discharge space for blue light is enlarged to increase the coverage of the associated phosphor materials. In this manner, the proportion of emitted red light, green light, and blue light of the PDP can be adjusted so as to promote color temperatures in the range of 7000K to 11000K.
Please refer to FIG.
1
.
FIG. 1
is a schematic diagram of a full-color plasma display panel
10
according to the prior art. The prior art PDP
10
comprises a first substrate
12
, a second substrate
14
positioned in parallel to the first substrate
12
, a discharge gas filling the space between the first substrate
12
and the second substrate
14
, and a plurality of first electrodes
18
, second electrodes
20
, and address electrodes
22
. Each of the first electrodes
18
and the second electrodes
20
are. alternately positioned on the first substrate
12
in parallel to each other. Each of the address electrodes
22
is positioned on the second substrate
14
perpendicular to the first electrodes
18
and the second electrodes
20
. Each of the first electrodes
18
and the second electrodes
20
comprises a support electrode
181
,
201
made of ITO, and a complementary electrode
182
,
202
made of Cr/Cu/Cr, a sandwiched structure with three metallic layers. The support electrode
181
,
201
is transparent to most visible light, but has great electrical resistance. The complementary electrode
182
,
202
has better conductivity and thus enhances the conductivity of the first electrodes
18
and the second electrodes
20
.
The PDP
10
further comprises a dielectric layer
24
that covers the first substrate
12
, a protective layer
26
covering the dielectric layer
24
, a plurality of barrier ribs
28
positioned on the second substrate
14
in parallel to each other for isolating two adjacent address electrodes
22
and defining a plurality of line-shaped discharge spaces
30
, and a phosphor layer
32
coating the surfaces of the second substrate
14
and the walls of the barrier ribs
28
that surround each discharge space. The phosphor layer
32
emits red light, green light or blue light. Each of the discharge spaces
30
comprises a plurality of unit display elements
34
arranged in matrix formation between the first substrate
12
and the second substrate
14
. All of the discharge spaces
30
are divided into a plurality of discharge space groups. Each of the groups comprises a red discharge space
30
R coated with a red phosphor layer
32
R, a green discharge space
30
G coated with a green phosphor layer
32
G, and a blue discharge space
30
B coated with a blue phosphor layer
32
B. Consequently, a plurality of red unit display elements
34
R are formed within the red discharge spaces
30
R, a plurality of green unit display elements
34
G are formed within the green discharge spaces
30
G, and a plurality of blue unit display elements
34
B are formed within the blue discharge spaces
30
B. Generally, one red unit display element
34
R, one green unit display element
34
G, and one blue unit display element
34
B form a pixel.
In order to improve the luminescence of blue light emitted from the PDP
10
, the width of the red discharge space
30
R is designed to be the narrowest. The width of the green discharge space
30
G is designed to be 1.2 times as wide as the width of the red discharge space
30
R. The width of the blue discharge space
30
B is designed to be 1.6 times as wide as the width of the red discharge space
30
R. Therefore, the red unit display element
34
R has smallest space, and the blue unit display element
34
B has the largest space. Hence, the coverage of the red phosphor layer
32
R is the smallest, and the blue phosphor layer
32
B has the largest coverage. Under these size ratios, the red, green and blue light will combine to form white light with a color temperature of about 11000K.
However, the widths of the different discharge spaces
30
are designed according to specific proportions. When the size of all of the discharge spaces
30
needs to be reduced to increase the resolution of the PDP
10
, the width of the red discharge space
30
R can become quite small. This not only increases the difficulty of manufacturing the barrier ribs
28
and the red phosphor layer
32
R, but can also lead to contraposition when sealing the first substrate
12
to the second substrate
14
. Furthermore, the red discharge space
30
R with a much smaller width can easily cause the discharge gas to cross talk with the adjacent discharge spaces
30
. This interference damages the electrical performance of the PDP
10
.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide a full-color PDP with a higher color temperature by adjusting the coverage of the phosphor layer, and thus avoid the above-mentioned problems of the prior art.
In a preferred embodiment, the present invention provides a plasma display panel that comprises a back substrate, a front substrate positioned on the back substrate, with a space between the facing surfaces of the front substrate and the back substrate. A plurality of barrier ribs are positioned in the space for defining a plurality of discharge space groups wherein each group comprises a first discharge space and a second discharge space. A first traverse rib is positioned in each first discharge space. A second traverse rib is positioned in each second discharge space wherein the transverse length of the second traverse rib is smaller than that of the first traverse rib. A first phosphor layer is coated on the surfaces of the back substrate, the first traverse ribs, and on the barrier ribs surrounding each first discharge space. A second phosphor layer is coated on the surfaces of the back substrate, the second traverse ribs, and on the barrier ribs surrounding each second discharge space. The coverage of the first phosphor layer is greater than that of the second phosphor layer. For a first discharge space and a second discharge space, a distance between the side of the first traverse rib and the center of the first discharge space is less than a distance between the side of the second traverse rib and the center of the second discharge space. Thus, the luminous intensity of the first phosphor layer is greater than that of the second phosphor layer.
It is an advantage of the present invention that the plurality of barrier ribs, cooperating with the traverse ribs of various size and placements, adjusts the coverage of the phosphor layers. This adjusts the coverage proportions of the phosphor layers coated within each discharge space to promote a color temperature of the PDP of up to 11000K.
These and o
Chien Yu-Ting
Huang Jih-Fon
Au Optronics Corp.
Colón German
Hsu Winston
Patel Nimeshkumar D.
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