Compositions – Inorganic luminescent compositions – Compositions containing halogen; e.g. – halides and oxyhalides
Reexamination Certificate
2001-01-08
2003-03-11
Koslow, C. Melissa (Department: 1755)
Compositions
Inorganic luminescent compositions
Compositions containing halogen; e.g., halides and oxyhalides
C252S30140R, C313S486000, C313S487000, C427S067000
Reexamination Certificate
active
06531074
ABSTRACT:
BACKGROUND OF THE INVENTION
Phosphor coatings for lighting applications typically require a binder phase in the phosphor suspension to obtain adequate phosphor adherence to the lamp envelope. One such commonly used binder is Aluminum Oxide C (AOC) which is a gamma phase aluminum oxide having a particle size on the order of 20 nanometers. While this material effectively promotes phosphor adherence, it does not contribute to the light output of the lamp and is a strong absorber of vacuum ultraviolet (VUV) radiation.
Other nanophase materials such as Y
2
O
3
:Eu and SiO
2
have been evaluated as alternatives to Aluminum Oxide C in phosphor systems for VUV applications, particularly neon gas discharge lamps. These materials are described in copending applications Ser. Nos. 09/162,192 and 09/483,435. While these materials promote phosphor adherence, neither material was shown to emit visible light under VUV excitation and only the nanophase Y
2
O
3
:Eu exhibited a weak visible emission under ultraviolet (UV) excitation. As such, neither material is able to contribute to the light output of a lamp which relies primarily on VUV excitation of the phosphor.
Thus, it would be an advantage to provide a nanophase binder material which emits visible light under both UV and VUV excitation.
SUMMARY OF THE INVENTION
It is an object of the invention to obviate the disadvantages of the prior art.
It is another object of the invention to provide a binder which promotes adherence in phosphor coatings and which emits visible light under UV and VUV excitation.
It is a further object of the invention to provide a method for coating a lamp in which the binder may be added directly to the phosphor coating suspension.
In accordance which an object of the invention, there is provided a luminescent nanophase binder comprising nanoparticles of a luminescent glass which emit visible light under UV and VUV excitation. In one aspect of the invention, the luminescent nanophase binder comprises SiO
2
nanoparticles doped with terbium or terbium and yttrium.
In accordance with another object of the invention, there is provided a method for coating a lamp comprising forming a colloidal dispersion of SiO
2
nanoparticles doped with terbium or terbium and yttrium, combining the colloidal dispersion with a suspension of a phosphor, coating the suspension on the lamp, drying the coating, and firing the coating at a temperature sufficient to remove water and residual organic material.
REFERENCES:
patent: 4707635 (1987-11-01), Tateyama et al.
patent: 4798681 (1989-01-01), Oversluizen et al.
patent: 6313578 (2001-11-01), Mishra et al.
Konrad et al., Chemical Vapor Synthesis and luminescence Properties of Nanocrystalline Cubic Y2O3:Eu,J. Appl. Phys., 86(6) (Sep. 1999) 3129-3133.
Sharma et al., Tailoring the Particle Size from &mgr;m→nm Scale by Using a Surface Modifier and Their Size Effect on the Fluorescence Properties of Europium Doped Yttris,J.Luminescence, 82 (1999) 187-193.
Goldburt et al., Size Dependent Efficiency in Tb doped Y2O3Nanocrystalline Phosphor,J.Luminescence, 72-74 (1997) 190-192.
Bhargava, R.N., Doped Nanocrystalline Materials—Physics and Applications,J.Luminescence, 70 (1996) 85-94.
Johnson Mary Ann
Trumble Cathy Shaw
Clark Robert F.
Koslow C. Melissa
Osram Sylvania Inc.
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