Electric lamp and discharge devices – Cathode ray tube – Screen
Patent
1983-03-09
1985-04-09
Demeo, Palmer
Electric lamp and discharge devices
Cathode ray tube
Screen
313473, 2523014S, H01J 2920, H01J 2926, C09K 1108
Patent
active
045104140
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a rare earth phosphor exhibiting sublinear current density-emission luminance characteristics, and an electron excited fluorescent display device using the phosphor.
More particularly, this invention relates to an europium and cerium activated rare earth oxysulfide phosphor which emits yellow to red light and which exhibits sublinear current density-emission luminance characteristics by the addition of predetermined amounts of activators, and an electron excited fluorescent display device provided with a fluorescent screen comprising the phosphor as the main part thereof.
BACKGROUND ART
Recently, electron excited fluorescent display devices such as cathode ray tubes and low-velocity electron excited fluorescent display devices are used for various purposes, and need exists for phosphors exhibiting linear, sublinear or superlinear excitation energy-emission luminance characteristics over wide range of the excitation energy.
The electron excited fluorescent display devices of this type include cathode ray tubes such as a multi-color cathode ray tube, a projection cathode ray tube and a high-luminance color cathode ray tube, multi-color low-velocity electron excited fluorescent display devices, and the like. These electron excited fluorescent display devices are provided with fluorescent screens comprising several kinds of phosphors mixed or combined together, and required to exhibit light emission characteristics corresponding to the characteristics of the phosphors. Particularly, strong need exists for a red emitting phosphor exhibiting sublinear excitation energy-emission luminance characteristics. For example, a multi-color cathode ray tube recently employed in terminal display units of a computer system, display units of an aircraft control system, and the like comprises a fluorescent screen constituted by two kinds of phosphors emitting light of colors different from each other; i.e. a phosphor exhibiting superlinear excitation energy-emission luminance characteristics when energy of excitation electron beam increases, and a phosphor exhibiting sublinear excitation energy-emission luminance characteristics when energy of the excitation electron beam increases. In the multi-color cathode ray tube, the color of light emitted from the fluorescent screen is changed by changing the energy of the excitation electron beam, thereby multi-color display is effected.
The aforesaid multi-color cathode ray tube is classified into two types according to the methods of changing the energy of the excitation electron beam. In one type thereof, the energy of the excitation electron beam is changed by changing the acceleration potential. In the other type, the energy of the excitation electron beam is changed by changing the current density. The former type is called potential modulation type multi-color cathode ray tube, and the latter type is called current modulation type multi-color cathode ray tube. The potential modulation type multi-color cathode ray tube is described, for example, in "Nikkei Electronics", July 2, 1973, pages 106 to 117, and the current modulation type multi-color cathode ray tube is described in Japanese Patent Publication No. 52(1977)-5225.
The current modulation type multi-color cathode ray tube is advantageous over the potential modulation type multi-color cathode ray tube in that the constructions of the electron gun and the electron gun control circuit, and the like are markedly simple. In spite of this advantage, the current modulation type multi-color cathode ray tube is not so widely employed for practical use as the potential modulation type multi-color cathode ray tube. This is because there are known few phosphors suitable for use in the current modulation type multi-color cathode ray tube, i.e. the phosphors exhibiting sufficiently superlinear or sublinear current density-emission luminance characteristics when the current density of the excitation electron beam increases.
As the phosphors exhibiting superlinear current density-emission lum
REFERENCES:
patent: 3574130 (1971-04-01), Mathers et al.
Fujino Sigeo
Hase Takashi
Toshinai Akio
Baker Joseph J.
Demeo Palmer
Ferguson Jr. Gerald J.
Fuji Photo Film Co. , Ltd.
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