Color picture tube

There are only a few commercial uses for europium. Europium oxide, (Eu O ), a compound of europium, is added to infra-sensitive phosphors to enhance the red colors on TV and computer-monitor picture tubes. It is also added to fluorescent light tubes to increase their efflciency, as well as to some materials to make lasers. Since it is a good neutron absorber, it is part of nuclear reactor control rods. Europium is an additive to the glue used on postage stamps, thus making it possible for the electronic sorting machines in U.S. postal offices to read the stamps. 

Transactions of the New York Academy of Sciences Figure 1. Principal components of color picture tube (5)... 

The consumption of rare earths in color TV is dictated in the first instance by the choice to use rare earth phosphors and the number of picture tubes produced. Within these constraints, several other factors tend to exert a downward influence on rare earth consumption. Reclaim, that is, reuse of phosphor coated on but not retained by the picture tube screen, is now universally practiced in the U.S, TV industry. Reclaim was not practiced at the time of the introduction of Eu-based reds. The high cost and uncertain availability of rare earth phosphors... 

In the coating of color picture tubes, the three components red, green, and blue are applied consecutively as dispersions in a photosensitive resin. This is then exposed to light via a shadow mask so that the resin on the exposed areas becomes water-insoluble. The phosphor on the unexposed areas is washed off with water. 

In color picture tubes, the final color is formed by additive mixing of red, green, and blue light. Each of the three phosphors (Table 58) is excited by its own modulated electron beam and emits light of intensity corresponding to the particular degree of excitation. The phosphors for color picture tubes have an average particle size of 8-10 pm. 

A television picture tube is a form of cathode ray tube in which the beam of j electrons is directed toward colored phosphors on the screen. A very low pressure is required to minimize the collisions between the electrons in the = beam and the gas molecules. Collisions and the resulting deflections of the j electrons would give a blurred, dim picture. 

Strontium, Barium Strontium was discovered near, and named after, the small town of Strontian, Scotland, in 1787. There are no commercial uses for the pure metal, but the carbonate salt, SrC03, is used in the manufacture of glass for color TV picture tubes. Barium is found principally in the minerals witherite (BaC03) and barite (BaSC ), after which it is named. Though water-soluble salts of barium are extremely toxic, barium sulfate is so insoluble that it is used in medicine as a contrast medium for stomach and intestinal X rays. Like strontium, barium metal has no commercial uses, but various compounds are used in glass manufacture and in drilling oil wells. 

Luminescent Pigments. This group of pigments covers a number of technologies and markets ranging from color television picture tubes to glow-in-the-dark ... 

Figure 3 shows the SPD of the old (A) and new (B) cool-white lamps. The new triphosphor lamp, based on phosphors developed for television picture tubes is much better at rendering color than the old monofluorophosphor (12). From their SPDs, one could hardly call them equivalent. They do however meet the criteria of color rendition, to "fool the eye", very well. 

The name comes from the town of Strontian in Scotland and was given to the element by Thomas Hope (1766-1844). There are many claims for the original discovery of strontium. William Cruikshank, in 1787, and Adair Crawford, in 1790, both examined strontianite (SrC03) and recognized that it had unique properties. Thomas Hope noted an unknown earth in 1791. Martin Klaproth presented a paper on a number of strontium compounds in 1793 and 1794. Richard Kirwan (1733-1812) examined a number of strontium compounds and presented his findings in 1794. It was Davy who isolated strontium metal, in 1808. Strontium does not occur in pure form in nature but is found in small quantities in many places. Some forms of strontium are radioactive, particularly 90Sr, which has been found in nuclear fallout. It can also be used in SNAP devices (Systems for Nuclear Auxiliary Power) as a power source. The main commercial use of strontium is in the glass of color television picture tubes. 

Compounds of europium and ytterbium are used in the picture tubes of color televisions. Neodymium is used in some high-power lasers. 

But such a phosphor is not currently available. It has been estimated that only about 85% of the hues found in Nature can be reproduced by a color picture tube. 

Color television s RGB system (Ernst Alexanderson) The RGB system uses three image tubes to scan scenes through colored filters and three electron guns in the picture tube to reconstruct scenes. 

FIGURE 5.112 Electrode arrangement of the Trinitron gun. (After Morrell, A. et al. 1974. Color Picture Tubes, pp. 91-98. Academic, New York.)... 

Barbin, R. and Hughes, R. 1972. New color picture tube system for portable TV receivers. IEEE Trans. Broadcast TVRec. BTR-18(3) 193 200. 

Blacker, A. et al. 1966. A new form of extended field lens for use in color television picture tube guns. IEEE Trans. Consumer Eke. (Aug.) 238 246. 

Donofrio, R. 1972. Image sharpness of a color picture tube by MTF techniques. IEEE Trans. Broadcast TV Rec. BTR-18(l) l-6. 

Godfrey, R. et al. 1968. Development of the permachrome color picture tube. IEEE Trans. Broadcast TV Rec.BTR-14(l). 

Hoskoshi, K. et al. 1980. A new approach to a high performance electron gun design for color picture tubes. 1980 IEEE Chicago Spring Conf. Consumer Electronics. 

Morrell, A. 1981. Color picture tube design trends. Proc. SID 22(l) 3-9. 

Morrell, A. et al. 1971. Color Television Picture Tubes. Academic, New York. 

Whitaker, J.C. 1993. Electronic Displays Technology, Design and Applications. McGraw-HiU, New York. Yoshida, S. et. al. 1973. A wide deflection angle (114°) Trinitron color picture tube. IEEE Trans. Elec. Dev. 

Yoshida, S. et al. 1974.25-V inch 114-degree Trinitron color picture tube and associated new development. 

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