Plasma display panel and method of making the same

Details Plasma display panel and method of making the same Plasma display panel and method of making the same

2002-04-26

2004-08-10

Dang, Hung Xuan (Department: 2873)

Electric lamp and discharge devices

With luminescent solid or liquid material

With gaseous discharge medium

C313S587000

Reexamination Certificate

active

06774558

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a plasma display panel (PDP) used in a display device and a method of making the panel.
BACKGROUND OF THE INVENTION
High-definition, large-screen television (TV) receivers such as high-definition TV have widely been demanded. Cathode ray tubes (CRT) are more favorable in resolution and quality of images than plasma displays or liquid crystal displays but not in its depth or its weight particularly for a large-screen type, 40 inches or larger. The liquid crystal displays successfully have a low power consumption and accepts a low driving voltage, but hardly have a large screen size and a wide viewing angle. The screen size of plasma displays increases to a greater size as 40 inches (for example, in page 7 of “Functional Materials”, in Vol. 16, No. 2, February 1996).
A conventional plasma display panel (PDP) and a display apparatus with the PDP will be described with referring to
FIGS. 7
to
10
.
FIG. 7
is a partial cross sectional perspective view of an image display region of the PDP.
FIG. 8
is a schematic plan view of the PDP with a front glass substrate removed, where display electrodes, display scan electrodes, and address electrode are illustrated not completely for ease of the description. An arrangement of the PDP will be explained referring to the drawings.
As shown in
FIGS. 7 and 8
, the PDP
100
includes a front glass substrate
101
and a back glass substrate
102
both made of boron-silicon-sodium glass by a floating method.
The front glass substrate
101
has N display electrodes
103
and N display scan electrodes
104
(
1
) to
104
(N) provided thereon. The display electrodes
103
and the display scan electrodes
104
(
1
) to
104
(N) are covered with a dielectric glass layer
103
and a protective layer
106
made of MgO, thus providing a front panel.
The back glass substrate
102
has M address electrodes
107
(
1
) to
107
(M) provided thereon. The address electrodes
107
(
1
) to
107
(M) are covered with a dielectric glass layer
108
and barriers
109
. Phosphor layers
110
R,
110
G, and
110
B are provided between the barriers
109
, thus providing a back panel.
The front panel and the back panel are bonded to each other by an air-tight sealing layer
121
which extends along the edges of the panels for sealing. A discharging space
122
is developed between the front panel and the back panel, and is filled with discharge gas. The electrodes
103
,
104
(
1
) to
104
(N), and
107
(
1
) to
107
(M) of the PDP are arranged in matrix pattern where a discharge cell is formed at each intersection between the scan electrode
104
and the address electrode
107
.
The electrodes of the front panel may generally includes transparent electrodes
111
and silver electrodes
112
on the front glass substrate
101
, or silver electrodes
113
on the front glass substrate
101
as shown in
FIGS. 9A and 9B
, respectively. The display apparatus having the PDP
100
of the above arrangement includes a driver
135
which includes a display driver
131
, a display scan driver
132
, and an address driver
133
which are connected to the corresponding electrodes of the PDP
100
, and a controller
134
for controlling their operation. As being controlled by the controller
134
, the drivers apply specific wave voltages between the display scan electrodes
104
and the address electrodes
107
(
1
) to
107
(M) for generating preliminary discharge at each discharge cell. Then, a pulse voltage is applied between the display electrodes
103
and the display scan electrode
104
for producing a main discharge which emits ultraviolet light at the discharge cell. The ultraviolet light excites the phosphor layer to light them. Since lighting, the discharge cells create an image in combination with not-lighted discharge cells.
The conventional PDP panel however includes the silver (Ag) electrodes where Ag may often migrate to the opposite electrodes (particularly under a high-temperature, high-moisture condition) when being energized, hence causing a short-circuit or a current leakage between terminals. It is well known that the migration of Ag under a high-temperature, high-moisture condition is accelerated when the front and back glass substrates are made of a float glass containing weight 3 to 15% of sodium (Na) or potassium (K).
FIGS. 11A and 11B
illustrate electrode leads of the conventional PDP.
In a PDP of a NTSC (VGA) type shown in
FIG. 11
, a distance between the address electrodes
107
(
1
) and
107
(
2
) is substantially 160 &mgr;m while a distance between the display scan electrodes
104
(
1
) and
104
(
2
) is substantially 500 &mgr;m. High resolution PDPs for high-definition TV or SXGA format have a distance between any two adjacent electrodes being ½ that of the NTSC (VGA) format type. Accordingly, the intensity of an electric field between the electrodes is doubled, and the migration of Ag takes place more often in the high-definition PDP.
In addition to the Ag-migration, the float glass substrates may cause Ag to be dispersed, as Ag ion, into the substrate material or dielectric material during the baking of the Ag electrodes or the baking of the dielectric glass layers. The dispersed Ag ion can be reduced by tin (Sn) or sodium (Na) ion in the glass substrates and Na or lead (Pb) ion in the dielectric glass and thus is deposited as colloidal particles. The Ag colloidal deposition may tint the glass with yellowish color (as depicted in J. E. Shelby and J. Vitko Jr., “Journal of Non Crystalline Solids”, Vol. 150 (1982), pp. 107-117), hence deteriorating a quality of an image on the panel. The yellowish Ag colloidal deposition, absorbing light of a wavelength of 400 nm, declines a luminance and a chrominance of blue color hence lowering a color temperature of the panel.
For elimination of the Ag-migration and the yellowish deposition, a technique where the sodium contained float glass with an SiO
2
film is coated is proposed. However, since having a thermal expansion coefficient of 4.5×10
−6
(1/° C.), which is smaller than that of the float glass of 8.0×10
−6
(1/° C.), the SiO2 film may create cracks after the baking process. This technique is thus imperfect for eliminating the Ag-migration and the yellowish deposition. In particular, the technique is less applicable to any high-definition display panel of the high-vision format or the SXGA format.
SUMMARY OF THE INVENTION
A plasma display panel (PDP) includes a first panel having a glass substrate fabricated by a floating method and a metal oxide layer provided on said glass substrate, a second panel facing said first panel to form a discharge space between said first panel, and an electrode containing Ag provided on said first panel.
As being prevented from a migration of Ag thus reducing a yellowish color change, the PDP can be improved in both luminance and image quality.


REFERENCES:
patent: 6097149 (2000-08-01), Miyaji et al.
patent: 6160345 (2000-12-01), Tanaka et al.
patent: 0965571 (1999-12-01), None
patent: 1093147 (2001-04-01), None
European Search Report for EP 02 00 9604, dated Aug. 19, 2002.
Shellby and Vitko, “Colloidal Silver Formation at the Surface of Float Glass,” Journal of Non-Crystalline Solids, vol. 50, 1982, 107-117.

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