Aluminate phosphor and process for its production, phosphor...

Details Aluminate phosphor and process for its production, phosphor... Aluminate phosphor and process for its production, phosphor...

2001-07-02

2003-07-01

Koslow, C. Melissa (Department: 1755)

Compositions

Inorganic luminescent compositions

Compositions containing halogen; e.g., halides and oxyhalides

C252S30140R, C313S486000, C313S467000

Reexamination Certificate

active

06585912

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an aluminate phosphor which emits a blue or bluish green color under excitation with ultraviolet rays or vacuum ultraviolet rays having a wavelength of at most 200 nm and a process for its production, a phosphor paste composition containing such a phosphor, and a vacuum ultraviolet ray excitation type light-emitting device (hereinafter referred to as a “VUV light-emitting device”) employing such a phosphor.
DISCUSSION OF BACKGROUND
In recent years, developments have been actively carried out for VUV light-emitting devices, wherein a fluorescent layer is formed inside of a light-transmitting envelope of e.g. glass, and a rare gas such as Ar, Xe, Ne or He is sealed therein, so that the phosphor in the fluorescent layer is excited by vacuum ultraviolet rays generated by the discharge of the rare gas, to emit lights. A typical example of such a VUV light-emitting device is a plasma display panel (hereinafter referred to as “PDP”) for displaying images or letters, or a rare gas lamp to be used as a light source for reading by a scanner.
PDP is one prepared in such a manner that flat front and rear plates made of e.g. glass are disposed to face each other; electrodes for display and partition walls are provided between them to define discharge spaces at constant distances; a phosphor layer is formed in recesses defined by the front and rear plates and the partition walls; the periphery of the front and rear plates is sealed to form an envelope; and the interior of the envelope is evacuated, and a rare gas is sealed in, so that an electric energy is applied to the electrodes to let the rare gas undergo discharge and thereby to excite the phosphor to generate visible lights, so that an observer can visually identify them. Here, by arranging recesses having a plurality of phosphor layers having different emission colors two dimensionally on a flat plate, full color display has been made possible.
On the other hand, the rare gas lamp is one wherein a fluorescent layer made of a phosphor (hereinafter referred to as a “VUV phosphor”) which emits light when excited by vacuum ultraviolet rays, is formed on an inner wall of a slender tube; both ends of the tube are sealed; and a rare gas such as Xe or Xe—Ne is sealed in, so that an electric energy is applied from electrodes formed at both ends of the slender tube or formed at the inside and outside of the slender tube, so that the phosphor is excited with vacuum ultraviolet rays generated by the discharge of the rare gas, to emit visible lights.
The fluorescent layer of PDP among such VUV light-emitting devices, is formed in such a manner that a phosphor for VUV and an organic resin solution such as butyl carbitol or terpineol having a resin such as ethyl cellulose dissolved therein, are kneaded to form a paste, which is then coated at predetermined portions in the cells by e.g. a screen printing method and dried and then, finally baked at a temperature of from about 300 to 550° C. mainly for the purpose of removing the organic component.
On the other hand, also the fluorescent layer of a rare gas lamp among VUV light-emitting devices, is formed in such a manner that a phosphor slurry having a phosphor for VUV suspended in an organic solvent such as butyl acetate containing a resin such as nitrocellulose, is coated on the inner wall of a slender tube, dried and then baked at a temperature of from about 400 to 600° C., to form a fluorescent layer.
As described above, for the formation of the fluorescent layer for a VUV light-emitting device, it is essential to carry out baking treatment of a coated layer in order to remove organic components in the phosphor coating layer. In this baking step, the phosphor is heated in the presence of organic components, whereby it undergoes deterioration, thus leading to a decrease of luminescence brightness. This deterioration of luminescence brightness by baking differs to some extent depending upon the type of the phosphor, and with an aluminate phosphor containing Eu as an activator, such as BaMgAl
10
O
17
: Eu or (Ba, Sr)BaMgAl
10
O
17
:Eu,Mn, having excellent emission characteristics with high luminance, as a blue or bluish green phosphor for a VUV light-emitting device, the degree of deterioration of luminance is large particularly in the layer-forming process, and an improvement in this respect has been desired.
SUMMARY OF THE INVENTION
The present invention has been made under these circumstances, and it is an object of the present invention to provide an aluminate phosphor which is less susceptible to deterioration of the luminescence brightness in the layer-forming step for a VUV light-emitting device, and a process for its production, a phosphor paste composition, and a VUV light-emitting device having a fluorescent layer made of such a phosphor.
The present inventors have conducted various studies on an aluminate phosphor using Eu as an activator, such as BaMgAl
10
O
17
:Eu or (Ba,Sr)MgAl
10
O
17
:Eu,Mn, and a process for its production, and as a result, have found that when an aluminate phosphor activated with Eu or coactivated with Eu and Mn, which contains sulfur, is used for a phosphor paste composition, the deterioration can be suppressed in the baking step for forming a phosphor layer of a VUV light-emitting device, whereby a blue or bluish green emission with high luminance inherent to the phosphor, can be maintained, and it has been made possible to provide a vacuum ultraviolet ray excitation type light-emitting device having high luminance.
Namely, the present invention provides:
(1) An aluminate phosphor activated with Eu or coactivated with Eu and Mn, which contains sulfur.
(2) The aluminate phosphor according to the above (1), wherein the aluminate phosphor is represented by the following formula and contains sulfur:
(M
1
1-x
Eu
x
)O.a(M
2
1-y
Mn
y
)O.bAl
2
O
3
wherein M
1
is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca, M
2
is Mg and/or Zn, and x, y, a and b are numbers within ranges of 0<x<1, 0≦y<1, 0<a≦2 and 4.5≦b≦5.5.
(3) The aluminate phosphor according to the above (2), wherein in the above formula, x, y, a and b are numbers within ranges of 0.05≦x≦0.5, 0≦y≦0.2, 0.9≦a≦1.1 and 4.8≦b≦5.2.
(4) The aluminate phosphor according to the above (3), wherein in the above formula, x, y, a and b are numbers such that 0.05≦x≦0.2, y<0.04, a=1.0, and b=5.0.
(5) The aluminate phosphor according to any one of the above (1) to (4), wherein the content of sulfur in the above phosphor is within a range of from 5 to 2,000 ppm, preferably from 50 to 500 ppm, more preferably from 50 to 200 ppm.
(6) A process for producing the aluminate phosphor as defined in any one of the above (1) to (3), which comprises firing a mixture of raw materials for the phosphor, to which sulfur or a sulfur compound is incorporated.
(7) The process for producing the aluminate phosphor according to the above (6), wherein the amount of the sulfur or the sulfur compound incorporated, is within a range of from 100 to 20,000 ppm, preferably from 150 to 15,000 ppm, more preferably from 200 to 10,000 ppm.
(8) The process for producing the aluminate phosphor according to the above (6) or (7), wherein at least one of the above sulfur compound contains at least one of metal elements constituting the above aluminate phosphor.
(9) A process for producing the aluminate phosphor as defined in any one of the above (1) to (3), which comprises firing a mixture of raw materials for the phosphor in a sulfurizing gas atmosphere.
(10) A phosphor paste composition comprising an organic binder resin solution and the aluminate phosphor as defined in any one of the above (1) to (5), dispersed in the solution.
(11) A vacuum ultraviolet ray excitation type light-emitting device comprising an envelope and a fluorescent layer formed inside of the envelope, so that the fluorescent layer is excited by vacuum ultraviolet rays generated by discharge of a rare gas sealed in the envelope,

Affiliated with

Also associated with

Rating

Aluminate phosphor and process for its production, phosphor... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Aluminate phosphor and process for its production, phosphor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aluminate phosphor and process for its production, phosphor... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3102601