Notes on a brilliant failure

Abstract

The article “Ernest Lawrence’s brilliant failure” by Joshua Roebke (Physics Today, March 2019, page 32) gives a historical account of early work by the Nobel recipient and his associates at the University of California, Berkeley, to invent color TV. An alumnus of both Berkeley and the TV industry (1964–2006), I was surprised and pleased to learn of that work. I had not realized that Sony’s Trinitron technology traces its origin back to Berkeley and Lawrence.However, I was shocked by several inaccuracies. The article is misleading regarding the basic principles of the color CRT (cathode-ray tube), and it does not present an accurate account of the pre-flat-panel display industry.The article claims that Sony’s Trinitron CRT was the best-selling television in the world and was the color TV most Americans grew up with. That is incorrect. From the beginning of color broadcasting in 1954 to the mid 2000s, RCA’s color CRT was the dominant one.Sony’s Trinitron was commercially introduced in 1968, 14 years after the start of the color TV industry. Virtually no other company manufactured color TVs with Trinitron displays. During the pre-flat-panel color TV era, Sony sold fewer than 300 million color TVs with Trinitrons; the rest of the industry globally sold well over 10 times as many sets with the RCA color CRT. Although RCA only manufactured in the US, it licensed its technology abroad; in several cases RCA provided direct engineering support for licensees’ manufacturing plants. All color TV manufacturers worldwide, including Sony, were RCA licensees.11. J. A. Castellano, SID Symp. Dig. Tech. Pap. 30, 356 (1999); https://doi.org/10.1889/1.1834031A. Monchamp et al., Cathode Ray Tube Manufacturing and Recycling: Analysis of Industry Survey, Electronic Industries Alliance (2001).The fundamental physical principles of the Sony and RCA color CRTs were identical. Both used three intensity-modulated electron guns to carry the three-color image information. Contrary to the article, the Trinitron did not use a single source for the three beams.The beams were scanned by a common magnetic deflection system. In both the Sony and the RCA devices, a metal mask with small openings was placed at a precise distance between the screen and the electron guns. The beams emerged from each opening at slightly different angles and landed on the screen at three slightly displaced, nonoverlapping locations, where a trio of red, green, and blue light-emitting phosphor elements were positioned. To prevent the excitation of adjacent phosphor elements, the mask transmission is necessarily restricted to less than ⅓.The Sony and RCA approaches used differently shaped masks. Sony’s was made of tensioned metal strips forming a vertical standing cylinder. RCA’s mask was best described as spherical. Thus the Sony guns were arranged horizontally, whereas the RCA ones had a triangle configuration. Both systems worked well. The price of color TVs was determined by the cost of the CRTs, which was mainly driven by the cost of their glass bulbs. Because the RCA approach was somewhat less expensive, it dominated the consumer market.ReferenceSection:ChooseTop of pageReference <<CITING ARTICLES1. J. A. Castellano, SID Symp. Dig. Tech. Pap. 30, 356 (1999); https://doi.org/10.1889/1.1834031, Google ScholarCrossrefA. Monchamp et al., Cathode Ray Tube Manufacturing and Recycling: Analysis of Industry Survey, Electronic Industries Alliance (2001). , Google Scholar© 2019 American Institute of Physics.