Board for plasma display with ribs, plasma display and...

Details Board for plasma display with ribs, plasma display and... Board for plasma display with ribs, plasma display and...

2000-07-21

2003-10-21

Patel, Vip (Department: 2879)

Electric lamp and discharge devices

With gas or vapor

Three or more electrode discharge device

C313S584000, C313S586000, C313S609000

Reexamination Certificate

active

06635992

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a board for a plasma display used in a large television set or computer monitor, a plasma display, and a production process thereof.
BACKGROUND ART
Since plasma displays (PDPs) allow high speed displaying and can be enlarged compared to liquid crystal panels, they are widely in such areas as OA apparatuses and information displays. As they are increasingly used in more areas, color PDPs having many fine display cells attract special attention.
In a PDP, plasma discharges are caused between anodes and cathodes located to face each other in discharge spaces formed between a front glass board and a rear glass board, to let the gas hermetically contained in the spaces emit light, for displaying.
A PDP is formed by bonding together a front glass board and a rear glass board respectively having electrodes, dielectric layer, etc. The rear glass board usually has a plurality of striped barrier ribs formed, and in the cells formed between the respectively adjacent barrier ribs, phosphor layer stripes are formed for color displaying in red, green and blue. These phosphor layer stripes are formed by coating the respective cells with an R (red) light emitting phosphor, G (green) light emitting phosphor or B (blue) light emitting phosphor usually by screen printing, and drying and firing the respective phosphors. To achieve a higher luminance, it is also practiced to form the phosphor layer stripes not only on the bottoms but also on the lateral faces of the cells, for forming a phosphorescent face (U.S. Pat. No. 5,674,553).
As described above, the cells for displaying R, G and B are formed between striped barrier ribs, and the barrier ribs are formed at a constant pitch. Therefore, the respective phosphor layer stripes of R, G and B are equally sized.
Presently developed red light emitting phosphors include Y
2
O
3
:Eu, YVO
4
:Eu, (Y, Gd)BO
3
:Eu, Y
2
O
3
S:Eu, g-Zn
3
(PO
4
)
2
:Mn, (ZnCd)S:Ag+In
2
O
3
, etc.
Green light emitting phosphors include Zn
2
GeO
2
:Mn, BaAl
12
O
19
:Mn, Zn
2
SiO
4
, LaPO
4
:Tb, ZnS:Cu, Al, ZnS:Au, Cu, Al, (ZnCd)S:Cu, Al, Zn
2
SiO
4
:Mn, As, Y
3
Al
5
O
12
:Ce, CeMgAl
11
O
19
:Tb, Gd
2
O
2
S:Tb, Y
3
Al
5
O
12
:Tb, ZnO:Zn, etc.
Blue light emitting phosphors include Sr
5
(PO
4
)
3
Cl:Eu, BaMgAl
14
O
23
:Eu, BaMgAl
16
O
27
:Eu, BaMg
2
Al
14
O
24
:Eu, ZnS:Ag+red pigment, Y
2
SiO
3
:Ce, etc.
As light emission characteristics of these light emitting phosphors, important are the luminance, emitted color and afterglow, but there is few perfect phosphors. Especially the luminances of blue light emitting phosphors are lower than those of red and green light emitting phosphors, and in the case of color display, a well-balanced color image is unlikely to be obtained disadvantageously. At present, a color display is designed in reference to the level of the blue light emitting phosphor.
DISCLOSURE OF THE INVENTION
The present invention provides a board for a plasma display capable of displaying a well-balanced brighter color image, a plasma display and a production process thereof.
In the conventional plasma display, since barrier ribs provided at a constant pitch and having the same width are used, the cells of respective R, G and B colors are equally sized, and for well-balanced color display, the luminance is adjusted in reference to the blue light emitting phosphor with the lowest luminance level. So, the capabilities of red and green light emitting phosphors are not sufficiently manifested. To obtain a brighter screen, efforts are made to produce improved blue light emitting phosphors higher in luminance, but no blue light emitting phosphor having the same luminance level as those of red and green light emitting phosphors has been developed yet.
Furthermore, in the case of full face light emission, the entire screen becomes yellowish since the luminance of blue is low. So, there is a problem that the beautiful white as displayed by a cathode ray tube cannot be reproduced.
The object of the present invention is to improve the brightness of the blue color emitting phosphor on the color screen for manifesting the red and green light emitting phosphors more brightly, thereby making the entire color image brighter and realizing a beautifully white screen.
To achieve the above object, the plasma display of the present invention is constituted as described below.
A glass board for a plasma color display, on which phosphor layer stripes emitting light of respective R, G and B colors are formed, and on which barrier ribs for partitioning the R, G and B phosphor layer stripes are formed, characterized in that the following relation is satisfied
Pb>Pr
where Pr is the distance between the respectively adjacent barrier ribs for forming a red light emitting phosphor layer, and Pb is the distance between the respectively adjacent barrier ribs for forming a blue light emitting phosphor layer, and that the height differences of the barrier ribs within the board face are within ±0.5~±6 &mgr;m in reference to the average height of the barrier ribs.
A board for a plasma display, on which striped barrier ribs for partitioning address electrodes and discharge spaces are formed, and on which phosphor layer stripes emitting red light, green light and blue light are formed in the grooves between the respectively adjacent barrier ribs, characterized in that phosphor layer stripes respectively emitting light of the same color are formed in respectively adjacent two or more grooves. The present invention also provides a plasma display using either of the boards as a rear board, and a process for producing either of the boards.
THE BEST EMBODIMENTS OF THE INVENTION
The suitable height of the barrier ribs of the plasma display is 80 &mgr;m to 200 &mgr;m. The pitch (P) of barrier ribs often used is in a range of 100 &mgr;m≦P≦500 &mgr;m. In the case of a highly precise plasma display, it is preferable that the pitch (P) of barrier ribs is 100 &mgr;m≦P≦250 &mgr;m, and that the rib width (L) is 10 &mgr;m≦L≦50 &mgr;m. Such highly precise barrier ribs can be formed by a sand blasting method or photosensitive paste method, but the latter photosensitive paste method is more preferable.
A material preferably used for forming the barrier ribs is a glass material containing the oxide of silicon and/or boron as an essential ingredient.
The conventional barrier ribs are formed in stripes at a constant pitch, and for color display, the cells formed between the respectively adjacent striped barrier ribs are coated respectively with a phosphor emitting light of each color, R, G or B. That is, pixels, each consisting of three colors of R, G and B, are disposed in stripes at a constant pitch. For example, if the pitch of barrier ribs is 150 &mgr;m, the respective light emitting regions of R, G and B are formed in the same size at this pitch.
Presently practically used typical phosphors include KX-504A for emitting red light, P1-G1S for emitting green light and KX-501A (respectively produced by Kasei Optonics K.K.) for emitting blue light. Among these phosphors, the luminance of blue light emitting phosphor KX-501A (chemical composition: (Ba, Eu)MgAl
10
O
17
) is at the level of ¼ to ½ compared to those of red light emitting phosphor KX-504A (chemical composition: (Y, Gd, Eu)BO
3
) and green light emitting phosphor P1-G1 S (chemical composition: (Zn, Mn)
2
SiO
4
).
Since the phosphors of respective colors are different in luminance like this, the luminance levels are matched in the cells of the same size as a conventional practice, but in this case, there is a problem that the luminances of red and green cannot be sufficiently utilized.
While the too large difference especially between the red phosphor layer and the blue phosphor layer in luminance is a problem in the conventional board for a plasma display, it was found that if the distance Pb between the respectively adjacent barrier ribs for the cells coated with the blue phosphor layer is made larger than the distance Pr between the respectively adjacent bar

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