A cathode-ray tube has a phosphor screen which is made by using a mixture of a long persistent phosphor and a short persistent phosphor. A light emission from the short persistent phosphor has a spike figure, so that a light pen can have sufficient sensitivity therefor, and a light emission from the long persistent phosphor is continuous within the one cycle period of the frame frequency, so that flicker is not noticeable.
A high-brightness phosphor screen and a method for forming the same are provided. The high-brightness phosphor screen having a low or middle working voltage, unlike a method of improving luminescent properties by use of a new synthetic phosphor, can be formed by simple deposition of a phosphor mixture that contains a proper ratio of a blue or green light-emitting phosphor for color image display and a bluish green light-emitting ZnO:Zn phosphor with high luminescent efficiency at low voltages.
According to the present invention, there is provided a color cathode ray tube of multi-purpose use in which as a red phosphor of a color phosphor screen, (ZnCd)S : Ag or (ZnCd)S : Cu phosphor of short decay time is added to rare earth phosphor to have an adding amount of 5 to 30 weight % relative to the total amount of red phosphor so that with respect to the red light emission, the high visibility brightness similar to that of the ordinary color television picture tube can be obtained. Also, since the brightness is lowered rapidly in the early stage of the light emission, the address detection can be carried out positively by, for example, a light pen pick-up.
In a shadow mask cathode ray tube for use with a light pen, the elemental phosphor areas emissive of red light comprise a blend of a red-emissive phosphor with silver-activated cadmium sulphide (CdS:Ag), the CdS:Ag being present in an amount from 10% to 30% by weight of the blend. In the preferred embodiment the blend comprises approximately 20% by weight of CdS:Ag and 80% by weight of industry standard P22R phosphor.
A color cathode-ray tube having a face glass (1) coated with a plurality of phosphors (6B, 6G, 6R) different in luminescent color, the face glass (1) containing a colorant imparting a selective characteristic for absorbing light in the wavelength regions between the luminescent wavelength regions of the phosphors, (6B, 6G, 6R) and a colorant suppressing the light transmittance in the visible region, wherein the light transmittances in the luminescent wavelength regions shorter than the highest-visibility wavelength region are at least about 5% lower than the light transmittance in the highest-visibility region, while the light transmittances in the luminescent wavelength regions longer than the highest-visibility wavelength region is higher than the light transmittance in the highest-visibility region.
A cathode-ray tube for color display comprises a face plate (1), a picture element layer (10) formed on an inner surface of the face plate and including two or more kinds of picture elements (5, 6 and 7), and a fluorescent material layer (4) formed between the picture element layer and the inner surface of the face plate and having a 10 percent afterglow time less than 50 microseconds. As necessary, a photoabsorptive material layer (2) may be provided in a matrix manner between the fluorescent material layer and the face plate. The picture element layer (10) performs a color display function and the fluorescent material layer (4) performs a communication function by means of a light pen. In case that a communication function by means of a light pen is not required, the step of forming the fluorescent material layer (4) may be omitted. Therefore, in manufacturing a cathode-ray tube requiring a communication function by means of a light pen and a cathode-ray tube not requiring such function, the same production line can be effectively utilized.
