Editing Trinitron (section)

===Trinitron===
[[File:Sony Trinitron logo.svg|150px|thumbnail|right|The Sony Trinitron logo used from 1992 to the 2000s]]
In the autumn of 1966, Ibuka finally gave in, and announced he would personally lead a search for a replacement for Chromatron. Susumu Yoshida was sent to the U.S. to look for potential licenses, and was impressed with the improvements that RCA had made in overall brightness by introducing new [[rare-earth element|rare-earth]] [[phosphor]]s on the screen. He also saw [[General Electric]]'s "Porta-color" design, using three guns in a row instead of a triangle, which allowed a greater portion of the screen to be lit. His report was cause for concern in Japan, where it seemed Sony was falling ever-farther behind the U.S. designs. They might be forced to license the shadow mask system if they wanted to remain competitive.<ref name=s46>''Sony'', p. 46</ref>

Ibuka was not willing to give up entirely, and had his 30 engineers explore a wide variety of approaches to see if they could come up with their own design. At one point, Yoshida asked [[Senri Miyaoka]] if the in-line gun arrangement used by GE could be replaced by a single gun with three [[cathode]]s; this would be more difficult to build, but be lower cost in the long run.{{how|date=December 2017}} Miyaoka built a prototype and was astonished by how well it worked, although it had focusing problems.<ref name=s46/> Later that week{{when|date=December 2017}}, on Saturday, Miyaoka was summoned to Ibuka's office while he was attempting to leave work to attend his weekly cello practice. Yoshida had just informed Ibuka about his success, and the two asked Miyaoka if they could really develop the gun into a workable product. Miyaoka, anxious to leave, answered yes, excused himself, and left. The following Monday, Ibuka announced that Sony would be developing a new color television tube, based on Miyaoka's prototype.<ref name=s47>''Sony'', p. 47</ref> By February 1967, the focusing problems had been solved, and because there was a single gun, the focusing was achieved with permanent magnets instead of a coil, and required no manual adjustments after manufacturing.{{citation needed|date=December 2017}}

During development, Sony engineer Akio Ohgoshi introduced another modification. GE's system improved on the RCA shadow mask by replacing the small round holes with slightly larger rectangles. Since the guns were in-line, their electrons would land onto three rectangular patches instead of three smaller spots, about doubling the lit area. Ohgoshi proposed removing the mask entirely and replacing it with a series of vertical slots instead, lighting the entire screen. Although this would require the guns to be very carefully aligned with the phosphors on the tube in order to ensure they hit the right colors, with Miyaoka's new tube, this appeared possible.<ref name=s47/> In practice, this proved easy to build but difficult to place in the tube – the fine wires were mechanically weak and tended to move when the tubes were bumped, resulting in shifting colors on the screen. This problem was solved by running several fine [[tungsten]] wires across the grille horizontally to keep the vertical wires of the grille in place.

The combination of three-in-one electron gun and the replacement of the shadow mask with the [[aperture grille]] resulted in a unique and easily patentable product. In spite of Trinitron and Chromatron having no technology in common, the shared single electron gun has led to many erroneous claims that the two are very similar, or the same.<ref>[http://www.scienceandsociety.co.uk/results.asp?image=10463866&wwwflag=2&imagepos=1 "Sony Trinitron color television receiver, c 1970"] is a common publication claiming that Trinitron and Chromatron are the same.</ref><ref name="Abramson2007">{{cite book|author=Albert Abramson|title=The History of Television, 1942 to 2000|url=https://books.google.com/books?id=TOMOmmrvwCcC&q=%22but+led+the+way+to+the+successful+chromatron%22&pg=PA117|date=15 September 2007|publisher=McFarland|isbn=978-0-7864-3243-1|page=117}}</ref>