Television digest with electronic reports (Jan-Dec 1953)

3 compatible system will be 15-in., sell for $1000. By late 1955 or early 1956, Stanton said, mass-production economies should reduce cost of sets by about 40%. The "CBS-Colortron" , as new tube is called, differs from RCA's as follows: In RCA tube, tiny phosphor dots are printed on a flat glass plate by silk screen process. A flat, thin metal plate (shadow mask) is pierced with holes, one for each 3 dots. Both plates are carefully aligned, bolted securely to heavy metal frame, placed inside tube envelope which is then sealed. In CBS tube, dots are placed directly on spherical face of tube envelope itself. Shadow mask is also curved, placed behind faceplate. Tube uses 3 guns, just as does RCA's. CBS claims its tube has many advantages over RCA's: that mask weighs 6 oz. , vs. 6 lbs. for the RCA mask-plate assembly; that its mask needn't be stretched, introducing many complexities; that it's far simpler to scan curved surface than flat ; that exhaustion of bulb is much more painstaking with RCA tube than with CBS's, results in more rejects; that CBS can get bigger picture with shorter tube; that CBS tube is less susceptible to overload damage, etc. Since placement of phosphors on faceplate is obviously desirable, if practical, we asked other tube makers why they haven't done it. Answer of one very experienced engineer: "It's far cheaper, quicker and easier to print the dots on a flat surface than to use a photographic process to put them on a curved screen. Then, there's only a small percentage advantage in scanning a curved surface instead of a flat one. Furthermore, it just isn't true that a bigger tube with a flat plate needs to be much longer. A 21-in. tube with a flat plate is about the same length as the 15-in. But the CBS tube is much lighter; that's certainly desirable." "It's another step, probably forward," said another expert. "I don't say that it's a big one. The real need is to get rid of those dots altogether." And RCA v.p. Ewen Anderson, addressing licensees Oct. 7, said: "The only difference is that the phosphor dots are on the rear of the faceplate instead of on a separate plate directly behind the faceplate. Following RCA's lead in adopting a 15-in. glass envelope, this tube is also enclosed in a 15-in. glass bulb and uses the principle of a faceplate sealed in with metal rings. As this tube uses the basic principles of RCA tri-color tube, it should — if it functions satisfactorily — work in the all-electronic compatible color receiver developed by RCA." Tube specifications: 18% lbs., 26%-in. long, 15%-in. diameter, 11%-in. screen, 45-degree deflection, 750,000 color phosphor dots. Voltages: anode 20,000, convergence electrode 9300, focus electrode 3100. Anode and convergence voltages must be maintained within 2%. Competing engineers say they're surprised at small usable screen area (about 104-sq. in.) and small deflection angle. The real trick in CBS tube is photographic process of putting dots on face. One colored phosphor is settled over entire screen and a photosensitive material is placed over it. Then, with curved shadow mask serving as negative, a point source of light is directed at the screen, fixing dots ; rest of phosphor is washed away. Process is repeated for other 2 colors. Theoretically, this should result in perfect alignment. The tube is aluminized. CBS-Hytron has experimented with shadow mask of "Photoform" glass produced by Corning, says it has advantages over metal. Color receivers employed during demonstration had 36 tubes, 4 rectifiers, CBS-Columbia pres. David Cogan told us. * * # # CBS's camera was well-kept secret. It's field-sequential, very similar to one used previously. It scans scene vertically, v.p. Dr. Peter Goldmark said, feeds signal to "Chromacoder" which converts output to NTSC specifications. Chromacoder has CR tube, dichroic mirrors, 3 pickup tubes. CBS officials didn't describe principles of the new device, but it's presumed to employ storage tubes. Other engineers say they've tried the idea through the years, always found it wanting, producing more problems than it solves. One big drawback has been proper storage tube, v/hich CBS may now have. Said one expert: "Never discount Goldmark." Advantages of this pickup equipment, CBS says, are in initial costs, operating expenses and simplicity. CBS camera costs $50,000 vs. $65,000 for RCA 3-image