Compositions – Inorganic luminescent compositions – Compositions containing halogen; e.g. – halides and oxyhalides
Patent
1997-06-25
2000-06-20
Koslow, C. Melissa
Compositions
Inorganic luminescent compositions
Compositions containing halogen; e.g., halides and oxyhalides
2523016S, 428403, 428404, 313467, 313468, 313461, 313463, 313486, 313503, C09K 1102, C09K 1156, H01J 2920, H05B 3314
Patent
active
060774584
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a phosphor, particularly, a phosphor film as a emissive type display, and to displays, particularly, a cathode-ray tube, an electroluminescence device, and a vacuum fluorescent display, using the phosphor film. The present invention also relates to spontaneously emissive type displays, particularly, an information video apparatus and an information video system.
BACKGROUND ART
Technologies for realizing high definition of cathode-ray tubes of projection type and direct view type are essential for implementing the future high definition television (hereinafter, referred to as "HDTV") broadcasting. Also, there have been strong demands toward improvement in characteristics of cathode-ray tubes used for televisions or video displays in the existing broadcasting. In particular, a projection type cathode-ray tube used as a large-sized video display needs to be improved in resolution and to be enlarged in angle of visibility. The enhancement in both definition and resolution, however, reduces brightness of a screen of a cathode-ray tube, and therefore, it must be accompanied by improvement in luminous efficiency of a phosphor used in the cathode-ray tube. Of course, the enhancement in both high definition and high resolution has come to be required for luminous type displays other than a cathode-ray tube, for example, an electroluminescence element and a vacuum fluorescent display.
Related art cathode-ray tubes of a projecting type have been described in "Singaku Technical Report, CPM93-32(1993), pages 1-6" and "Journal of Luminescence, 48/49 (1991), pages 43-48".
Improvement in brightness of a projection type cathode-ray tube has been mainly performed by enlarging the particle size of phosphor particles and increasing the thickness of a phosphor film. The increased thickness of a phosphor film, however, causes such a problem as shown in FIG. 9. That is, for a thick phosphor film, the diameter of an electron beam (luminous spot diameter) is apparently spread by the scattering of light due to the film structure shown in FIG. 9, resulting in the degraded resolution. In FIG. 9, a phosphor film 72 (thickness indicated by numeral reference 94: 50 .mu.m) is formed of phosphor particles having diameters of 10-13 .mu.m on a face plate 71, and an Al reflection film 91 is provided on the phosphor film 72. In the case where an electron beam (diameter indicated by reference numeral 92: 110 .mu.m) impinges on the phosphor film 72 through the Al reflection film 91 and ejects from an opposing surface of the face plate 71 to the phosphor film 72, a profile 95 of a luminous spot of the electron beam becomes thicker than the incident electron beam as shown in FIG. 9. Concretely, the luminous spot diameter 93 becomes 180 .mu.m, which is 70 .mu.m thicker than the incident electron beam diameter 92 (110 .mu.m). The beam increment (70 .mu.m) indicated by reference numeral 96 is produced depending on scattering of light in the phosphor film 72 and luminous saturation of the phosphor. In FIG. 9, reference numeral 97 indicates a locus of fluorescence due to scattering and reflection of light in the phosphor film 72.
The reason why the above technique of increasing the thickness of a phosphor film, which has a problem in terms of degradation of resolution, is applied to a phosphor film of a cathode-ray tube, is that the substantial efficiency of the phosphor is reduced by increasing the density of an excitation current of the cathode ray tube. Specifically, the gradient (current coefficient) of a relationship of a luminous intensity (logarithmic scale) to an excitation current intensity (logarithmic scale) of a phosphor is deviated from the linearity, and the increase in luminous intensity becomes blunt (that is, brightness is saturated). Such a reduction in current coefficient is one of important problems of the existing projecting type cathode-ray tube. In particular, a large problem resides in reduction in current coefficient of a blue component of a blue phosphor (ZnS: Ag) in a high
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Derwent Abstract For JP59-202284.
Matsukiyo Hidetsugu
Shiiki Masatoshi
Toyama Hisashi
Hitachi , Ltd.
Koslow C. Melissa
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