The Consumer Electronics Hall of Fame: Sony Trinitron

The Sony Trinitron not only established Sony as a first-rank technology innovator, it also established Japan as a world-class source of advanced electronics

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The Trinitron, unveiled by Sony in 1968, was the first major technological advance in color television sets since they were first commercialized in the early 1950s. Like so many innovations, it evolved out of multiple failures.

Color in TVs was achieved by exciting phosphor dots on the internal side of TV screens. The main elements in original color TV sets included, from the back of the cabinet to the front: three electron emitters, or “guns,” arranged in a triangle; these pointed at a barrier, called a shadow mask, that was perforated with holes; beyond that was the screen with its phosphors.

The screen was patterned with millions of tiny phosphorescent dots, arranged in trios. When electrons hit the dots, they emitted light. In each trio was three dots, chemically created so that one emitted red light, one green, and one blue. In theory, any color visible to the human eye can be created with different combinations of red, green and blue (RGB) light.

Each of the three electron guns was aimed at only one phosphor dot in each of the RGB triplets. The color that each triplet displayed could be selected by firing the guns to light up the right combination of dots to create the desired color. Electrons from the guns scanned back and forth many times per second, lighting the appropriate dots to make a color image on the screen. To make moving images, the screen had to be lit, or “painted,” many times per second. This “refresh rate” was typically 60 frames or more per second.

There was a problem, however. Aiming each gun at only one dot in each trio would work if the guns emitted electrons in a tight beam. They didn’t. The electron “beam” was more of a spray.

The way TV manufacturers dealt with that was by incorporating the shadow mask. The holes in the mask would allow through only those electrons from each gun traveling the path to the gun’s designated dot in each triad. All the other electrons were blocked.

The scheme worked. Mostly. The electron guns had to be in perfect alignment, however, and they got out of alignment often enough that they occasionally needed professional adjustment. Furthermore, the shadow masks blocked a lot of electrons that otherwise could have been used to make each RGB trio phosphoresce more intensely. Color TV screens weren’t as bright as they could be, in part because of the wastage of all those charged particles.

There were multiple angles to work to improve color TV. For example, RCA, the world’s leading manufacturer of television sets at the time, began using rare earths that would phosphoresce more brightly. General Electric rearranged the guns into a row (instead of a triangle) and was getting good results. A tiny U.S. outfit called Chromatic Television Laboratories was on yet a different tack. Basing its approach on an idea of renowned physicist Ernest O. Lawrence of the University of California, Berkeley, it tried to use a single electron gun and replace the shadow mask with a grate of charged vertical wires. This technology, which was called a Chromatron, also created a brighter picture, because it had no shadow mask, though Chromatic could not get the technology to work consistently.

Sony was determined to never be a copycat (or pay royalties). At a 1961 trade show sponsored by the Institute of Radio Engineers, one of IEEE’s predecessor societies, Sony executives saw a Chromatic set in operation. They negotiated a license to the technology more or less on the spot. Sony built a TV based on the purchased technology and brought it to market in 1965.

Sony’s Chromatrons provided a great color picture, but they couldn’t be reliably mass-produced and cost the company so much more than it was making on them that the business was threatening to sink Sony, according to Susumu Yoshida, an engineer who worked on the Chromatron and Trinitron. The company had to find another way to make color TVs.

The four lead engineers on the Trinitron project were Yoshida, Masaru Ibuka, Senri Miyaoka, and Akio Ohgoshi. Yoshida claims credit for the breakthrough idea for the Trinitron. He liked GE’s approach to the electron emitters, of having a linear system instead of the triangular configuration, because that made it easier to converge the three beams. But he also liked having one gun (as the Chromatron did) because it was less expensive than having three. Yoshida wondered if it would be possible to put three cathodes in a line inside a single gun?

Long story short: It was. It took some additional tweaks, including the installation of deflection plates above the gun to help focus the electron beams and developing a chemical etching process to create an aperture grill, which performed the same task as the Chromatron’s charged-wire grill, and in much the same way. But the system worked, it could be mass-produced at an acceptable cost, and it was stable, in that it would rarely if ever have to be professionally adjusted after it was sold. And, most importantly, it provided a brilliant color picture.

Introduced in 1968, the Trinitron was an instant hit. The improvements it offered in picture quality justified charging a premium. In 1973, it became the first consumer electronics device to win an Emmy. Sony eventually sold 280 million Trinitrons, as both TVs and, later, computer monitors.

If the Trinitron was nothing more than a huge leap in TV technology and a monster commercial success, that would be enough to assure it a place in our Hall of Fame. But it was so much more than that. It vaulted Sony into the first rank of technology providers. Trinitron sales helped finance Sony’s run of success that few if any other consumer electronics manufacturers have matched for innovation across such a wide variety of products over so many decades. Furthermore, Sony’s success was Japan’s too. Prior to the Trinitron, most electronic products from the country were inexpensive and of suspect quality. The Trinitron was one of the foundational products establishing Japan as a world-class source of advanced electronics.

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