Electric lamp and discharge devices – Cathode ray tube – Screen
Patent
1985-06-28
1987-08-25
DeMeo, Palmer C.
Electric lamp and discharge devices
Cathode ray tube
Screen
2523016S, H01J 2920
Patent
active
046895205
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
TECHNICAL FIELD
The present invention relates to a color cathode ray tube and particularly to a color cathode ray tube which can be used as an ordinary color television picture tube and also a color display apparatus of light pen pick-up system for a terminal display apparatus.
BACKGROUND ART
In a so-called character display apparatus for displaying very small patterns such as character, symbol, figure and so on in a terminal display apparatus, in order to obtain a reproduced picture of high definition, the interlaced scanning system of 2 field and 1 frame type is not adopted but such a scanning system is employed in which the respective scanning lines are sequentially scanned because the positional displacement between the adjacent scanning lines of each field must be avoided.
Recently, in accordance with the introduction of home computers, a single cathode ray tube for multi-purpose use has been developed which can be used as an ordinary color television picture tube suitable for a terminal display apparatus and which can be changed from the ordinary television picture receiving mode to the non-interlaced scanning mode with the frequency of 60 Hz.
In such color cathode ray tube of multi-purpose use, particularly when it is used as the terminal display apparatus for carrying out the address detection by a light pen pick-up, since it is necessary to detect the moment an electron beam passes the phosphor screen by this light pen pick-up, so long as a certain output level can be obtained, the phosphor is required to have a relatively short decay time so as to increase the pick-up accuracy.
However, in the color phosphor screen of the color cathode ray tube used as the ordinary color television picture tube, the decay time of the green and blue phosphors is around several tens microseconds. So, the address of such color phosphors can be detected by light pen pick-up system. Whereas, rare earth phosphors generally used as red phosphors, for example, Y.sub.2 O.sub.2 S:Eu or Y.sub.2 O.sub.3 :Eu or YVO.sub.4 :Eu have a relatively long decay time as long as 1 milli second (decay time is the time until the brightness of phosphor decreases to 1/10 the brightness of the initial light emission). Thus such red phosphor will interfere with the address detection.
As described above, the present invention is to provide a color cathode ray tube of multi-purpose use which can be used as the terminal display apparatus of, for example, light pen pick-up system and in which the address detection can be carried out positively.
In other words, the present invention is to provide a color cathode ray tube which can positively carry out the address detection by the light pen pick-up system without substantially changing chromaticity and brightness of the red phosphor and without interfering with the use of it as the ordinary color television receiver.
DISCLOSURE OF INVENTION
According to the present invention, similarly to the ordinary color cathode ray tube, a phosphor screen thereof is formed by repeatedly and sequentially coating red, green and blue phosphors to have a predetermined pattern, for example, stripe-shape or do-shape in a predetermined order. Particularly in the present invention, (ZnCd)S:Ag or (ZnCd)S:Cu phosphor is mixed to the usual rare earth phosphor, for example, Y.sub.2 O.sub.2 S:Eu, Y.sub.2 O.sub.3 :Eu and YVO.sub.4 :Eu with the mixing ratio of 5 to 30 weight % relative to the total amount of red phosphor and then the color phosphor screen is formed by using such red phosphor.
BEST MODE FOR CARRYING OUT THE INVENTION
As earlier noted, in the color cathode ray tube of the present invention, the color phosphor screen thereof is formed by respectively coating red, green and blue phosphors with predetermined order and alignment. In this case, the blue phosphor is made of, for example, ZnS:Ag and the green phosphor is made of, for example, ZnS:CuAl. The red phosphor is made by mixing red phosphor, (ZnCd)S:Ag (ZnS:CdS=2:8) to the prior art rare earth phosphor Y.sub.2 O.sub.2 S:Eu with the m
REFERENCES:
patent: 3742291 (1973-06-01), Yamada
patent: 4151442 (1979-04-01), Koga et al.
patent: 4424467 (1984-01-01), Masuda et al.
Kuboniwa Shigeo
Okada Hideki
Tamura Michio
DeMeo Palmer C.
Sony Corporation
Wieder K.
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