Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2001-09-07
2003-09-09
O'Shea, Sandra (Department: 2875)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S486000, C252S30140R
Reexamination Certificate
active
06617788
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to display devices for broadcast receivers with a plasma discharge display panel, computer instruments and the like, including the display panel itself, and light sources having a fluorescent lamp such as the back light of a liquid crystal display or the like.
In recent years, display devices of broadcast receivers, computer instruments and the like using a plasma display panel (hereinafter, referred to as PDP) which is a plasma discharge display panel have come to be mass-produced.
A PDP makes a color display by emitting light from a phosphor placed in a discharge space by using a short-wavelength ultraviolet light generated in the negative glow region in a micro discharge space containing a rare gas (when xenon is used as the rare gas, its resonance line is at 147 nm or 172 nm) as an excitation source.
In a PDP, a resonance line of a rare gas of which the emission wavelength is shorter than that of mercury vapor resonance line (253.7 nm) or the like is used as the excitation source of the phosphor, and the lower limit wavelength thereof is the resonance line of helium (58.4 nm).
The structure of the gas discharge cell of a PDP is, for example, as shown in “Techniques and Materials of Color PDP/published by C.M.C. K.K.”, and the typical structure is shown in FIG.
7
.
FIG. 7
is an exploded perspective view illustrating the structure of a general surface discharge type color plasma display (PDP), wherein a rear glass substrate
20
on which a red (R) phosphor layer
24
, a green (G) phosphor layer
25
and a blue (B) phosphor layer
26
are formed and a front glass substrate
10
made of a glass substrate are laminated to each other to form an integrated body.
The front glass substrate
10
has a pair of display electrodes
11
and
12
formed on a surface confronting the rear substrate
20
in parallel with each other with a constant distance. The display electrodes
11
and
12
are transparent electrodes. Opaque bus electrodes
13
and
14
are provided in combination therewith in order to supplement the electrical conductivity of display electrodes
11
and
12
.
The display electrodes
11
,
12
and the bus electrodes
13
,
14
are coated with a dielectric substance layer
15
, and the dielectric substance layer
15
is coated with a protective film
16
made of magnesium oxide (MgO).
Having a high sputter resistance and a high secondary electron releasing coefficient, the magnesium oxide (MgO) protects the dielectric substance layer
15
for ac operation and functions so as to lower the discharge-starting voltage.
The rear glass substrate
20
has, on the surface confronting the front glass substrate
10
, an electrode group consisting of address electrodes
21
making a right angle with the display electrodes
11
and
12
of the front substrate
10
, and the address electrodes
21
are coated with dielectric substance layer
22
. On the dielectric substance layer
22
separation walls (ribs)
23
are provided partitioning the address electrodes
21
from one another in order to prevent spread of the discharge or to limit the domain of discharge. The ribs
23
are made of a low-melting glass, and they are all the same in interval, height and shape of side wall.
The groove surfaces between the ribs
23
are stripe-wise coated with phosphor layers
24
,
25
and
26
each emitting a red-colored, green-colored and blue-colored light, successively. Each of the phosphor layers
24
,
25
and
26
is formed by mixing a particulate phosphor with a vehicle to prepare a phosphor paste, forming each paste into stripe-like coatings after forming address electrode
21
, dielectric substance layer
22
and rib
23
on the rear glass substrate
20
by the method of screen printing or the like, and thereafter removing the volatile component by baking or the like.
Into the discharge space between the front substrate
10
and the rear substrate
20
, a discharge gas such as helium, neon, xenon or the like (not shown in the drawing) is sealed.
In this PDP, a gas discharge is carried out by selecting a discharge cell (unit light emitting area or discharge spot) from one of the display electrodes
11
and
12
(for example, display electrode
12
) and the address electrode
21
, and repeatedly carrying out gas discharge from the selected discharge cell by a sustaining discharge between the display electrodes
11
and
12
.
The gas discharge generates a vacuum ultra-violet light, which excites the phosphor layer of the area to emit a visible light. Thus, a color display can be obtained as a combination of light emissions from the unit light-emitting areas each having the phosphor layers
24
,
25
and
26
, corresponding to the three primary colors (red, green and blue).
Luminance of color PDPs has been improved year by year, until it has reached about 400 cd/m
2
at the present time. However, a color PDP is still lower in luminance than the direct-view type CRT color television of which peak luminance is 600 to 1,000 cd/m
2
, and a further improvement of the performance of a PDP is urgently needed.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide green- and blue-light emitting materials and a phosphor film with which a high-performance PDP can be realized.
It is another object of the present invention to provide a light source having a high-performance fluorescent lamp.
The present invention provides a phosphor capable of emitting a visible light under an exciting light of which main component is ultraviolet light having a wavelength ranging from 100 nm to 400 nm, which is represented by the following composition formula:
(Ba
1-a-b-c
Ca
a
Sr
b
M
c
)O.
x
MgO.
y
Al
2
O
3
wherein M is at least one element selected from the group consisting of Eu, Tm, Lu and Mn, and a, b, c, x and y satisfy the following conditions:
0<a≦0.01,
0<b≦0.01,
0.01≦c≦0.3,
0≦x≦2.2, and
4.0≦y≦12.0.
The present invention further provides a display device and a light source using the above-mentioned phosphor.
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A. Ohtsuka, “Technology & Materials of Color Plasma Display Panel”, published by C.M.C. K.K., 1996, pp. 41-49.
K. Yoshikawa et al., “S16-2 A Full Color AC Plasma Display with 256 Gray Scale”, Japan Display, 1992, pp. 605-608.
Okazaki Choichiro
Shiiki Masatoshi
Suzuki Teruki
Dong Dalei
Hitachi , Ltd.
Miles & Stockbridge P.C.
O'Shea Sandra
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