Compositions – Inorganic luminescent compositions – Compositions containing halogen; e.g. – halides and oxyhalides
Utility Patent
1996-09-25
2001-01-02
Koslow, C. Melissa (Department: 1755)
Compositions
Inorganic luminescent compositions
Compositions containing halogen; e.g., halides and oxyhalides
C252S30140R, C252S30160R, C252S30160F, C313S467000, C313S468000, C313S496000
Utility Patent
active
06168729
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Industrial Invention
The present invention relates to a fluorescent material that is excited for luminescence by a low-speed electron ray so that it keeps a luminance characteristic excellent and more particularly to a fluorescent display device composed to have the fluorescent material.
2. Description of the Related Art
It is considered that a fluorescent display device having a filament type oxide cathode or a field emission type cathode served as an electron source should preferably have an anode voltage in the range of 30 V to 2 KV. If the fluorescent material is excited for luminescence by the so-called low-speed electron line of 2 KV or lower, it is important to keep the resistance of the fluorescent material low and a luminance characteristic, that is, dependency on a voltage density and a current density excellent. Another important point is that the fluorescent material does not contain such a material as having an adverse effect on the cathode served as the electron source. However, There is no fluorescent material that meets individually these important conditions.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a fluorescent material that has not an adverse effect on a cathode but an excellent luminance characteristic in the fluorescent display device having an anode voltage of 2 KV or lower and a fluorescent display device composed to have such a fluorescent material.
According to a first aspect of the invention, a fluorescent material is composed of a mixture of a highly resistive fluorescent material having excellent current and voltage characteristics in an anode voltage of 1 KV or higher and a low resistive fluorescent material having excellent current and voltage characteristics in an anode voltage of 1 KV or lower and is excited by the rush of electrons accelerated by the anode voltage of 2 KV or lower.
According to a second aspect of the invention, the fluorescent material is composed of the highly resistive fluorescent material that is a selective one of the materials of Y
2
O
3
:Eu, YVO
4
:Eu, and Cd
2
O
3
:Eu and the low fluorescent material that is a selective one of the materials of SnO
2
:Eu and SrTiO
3
:P, X (X=Al, Ga).
According to a third aspect of the invention, the fluorescent material is composed of the highly resistive fluorescent material that is a selective one of the materials of Y
3
(Al, Ga)
5
O
12
:Tb, Y
2
SiO
5
:Tb, InBO
3
:Tb, and Zn
2
SiO
4
:Mn and the low resistive fluorescent material that is Zn(Ga, Al)
2
O
4
:Mn.
According to a fourth aspect of the invention, the fluorescent material is composed of the highly resistive material that is a selective one of the materials of Y
2
SiO
5
:Ce, CaWO
4
, (Ca, Mg)SiO
3
:Ti, (Y, Sr)TaO
4
:Nb, and Zn
2
SiO
4
:Ti and the low resistive material that is a selective one of the materials of ZnGa
2
O
4
:Li and ZnO:Zn.
According to a fifth aspect of the invention, a fluorescent display device arranged to accelerate electrons emitted from an electron source at a driving voltage of 2 KV or lower and rush the electrons to an anode for making the fluorescent material of the anode luminous is composed of the fluorescent material according to the first aspect of the invention.
According to a sixth aspect of the invention, the fluorescent display device composed according to the fifth aspect of the invention includes a filament type oxide cathode served as the electron source.
According to a seventh aspect of the invention, the fluorescent display device composed according to the fifth aspect of the invention includes a field emission type cathode served as the electron source.
As described above, the fluorescent material according to the present invention is composed of a mixture of the highly resistive fluorescent material and the low resistive fluorescent material. Hence, the fluorescent material does not have an adverse effect on the cathode in the fluorescent display device operated at a driving voltage of 2 KV or lower and makes it possible to display the excellent luminance characteristic and tone.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.
REFERENCES:
patent: 2628201 (1953-02-01), Smith
patent: 4303913 (1981-12-01), Tohda et al.
patent: 5619098 (1997-04-01), Toki et al.
patent: 6090309 (2000-07-01), Chadha et al.
patent: 5-59359 (1993-03-01), None
Itoh Shigeo
Kataoka Fumiaki
Sato Yoshitaka
Toki Hitoshi
Breiner & Breiner
Futaba Denshi Kogyo K.K.
Koslow C. Melissa
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