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A 1985 27" Trinitron
A 1985 27" Trinitron

Trinitron is Sony's brand name for its line of aperture-grille-based CRTs used in television sets and computer displays. One of the first truly new[vague] television systems to enter the market since the 1950s, the Trinitron was announced in 1968 to wide acclaim for its bright images, about 25% brighter than common shadow mask televisions of the same era. Constant improvement in the basic technology and attention to overall quality allowed Sony to charge a premium for Trinitron devices into the 1990s.[citation needed]

Patent protection on the basic Trinitron design ran out in 1996, and it quickly faced a number of competitors at much lower prices. Sony responded by introducing their flat-screen FD Trinitron designs (WEGA), which maintained their premier position in the market into the early 2000s.[citation needed] However, these designs were surpassed relatively quickly by plasma and LCD designs. Sony removed the last Trinitron televisions from their product catalogs in 2006, and ceased production in early 2008. Video monitors are the only remaining Trinitron products being produced by Sony, at a low production rate, although the basic technology can still be found in downmarket televisions from third parties.[citation needed]

The name Trinitron was derived from trinity, meaning the union of three, and tron from electron tube, after the way that the Trinitron combined the three separate electron guns of other CRT designs into one.[1]

Close-up of phosphor bars on a 14" Sony Trinitron television.
Close-up of phosphor bars on a 14" Sony Trinitron television.

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In 1960, the fledgling Sony company in Japan decided to get into the television business. Their first foray into television was a remarkable achievement in and of itself, being the first completely transistorized television. The TV8-301 wasn’t really a commercial hit, but it was a technical feat. And just a year later, Sony’s dealers were putting pressure on them to develop a color TV Sony was understandably reluctant as color TV sales at the time were abysmal in Japan, but the sales department managed to exert sufficient pressure on the engineering department to actually start work. Sony’s visit to the 1961 IEEE trade show resulted in a glimpse of the Autometric company’s Chromatron tube. This picture tube worked in a completely different fashion than the shadow mask picture tubes of the time. Rather than use three electron guns and a matrix of holes to create the separation like the standard shadow mask picture tube did, the Chromatron used a single electron gun combined with a vertical grille of electrically charged wires at the front of the tube. In essence, the Chromatron relied heavily on electronics to focus the electron beam onto the correct color. The beam was normally focused onto the vertical green phosphor stripes present at the front of the screen. But the deflecting wires, placed about a half inch behind the phosphors, could push the beam to either side, and light up the adjacent phosphor stripe. The pattern of these phosphor stripes on a Chromatron tube, sometimes called a Lawrence tube, were arranged as RGB - BGR. This was necessary due to the way the deflecting wires worked. Without a charge, the beam wouldn’t be a tightly focused and would light all three phosphors together. But by placing a charge between pairs of wires, you would get both a tighter beam and the ability to push it left and right to control the alternate colors. Placing a single green stripe between two reds and two blues made this easier to accomplish, as the direction the beam was pulled would reverse as it crossed each pair of deflection wires, as their individual voltage potential remained constant. Using an RGB-RGB pattern would require constantly reversing the wire grid’s charge, which would be a nightmare with the electronics of the time. Already there was a lot of added complexity, as with a single electron beam, it needed to be precisely modulated when producing a color image to ensure it fired with the correct intensity as it repeatedly changed what color component it was illuminating. The huge advantage of this chromatron tube was a much brighter picture than conventional tubes using a shadow mask. Even though it used just one electron gun, none of the beam’s energy was lost with this system, as all of it passed through the focusing wires. The Chromatron also benefited from minimal required convergence tweaking. This made the Chromatron tube much easier to configure in the factory, and less likely to experience convergence problems requiring adjustment over time. Remember, this was only seven years after the first color television was mass produced, so we’re dealing with brand new technologies with patents and licensing to go along with them. Sony saw both the better picture results of this tube and the possibility to skirt around licensing costs and leapt at the chance to take over the project. Sony bought the entire Autometric operation from Paramount Pictures, who was behind it. But they’d soon discover that while the Chromatron tube was a fabulous device once built, it was a veritable pain in the ass to produce. It took until 1964 for the first Chromatron television to actually be mass produced. And Sony sold each one at a loss. They were put on the market for a reasonable 198,000 Yen, but cost 400,000 Yen to build. That’s obviously not sustainable, but Sony had faith that if they just stuck with it, they could get the manufacturing costs down by perfecting the process as the production line matured. Well, they couldn’t. It continued to be a nightmare. So in 1966 Masaru Ibuka, Sony’s president and co-founder, led the way to find a replacement for the Chromatron. Part of the reason was that General Electric’s Porta-Color TVs had introduced an improved shadow mask design and new arrangement of electron guns. These picture tubes moved the electron guns from a triangle arrangement to an in-line arrangement, and shifted from the dot-pattern of the original CRT designs to the vertical triad design you see here. The result was a much brighter picture that was close to what the Chromatron was producing, and also eliminated many of the convergence problems conventional shadow mask tubes suffered from. So now Sony was stuck with a money-losing product that wasn’t that much better than the competition. The engineers at Sony would alter some of the ideas from the Portacolor and merge them with the Chromatron’s design. Susumu Yoshida asked engineer Senri Miyaoka if the three in-line electron guns could be replaced by a single electron gun with three individual cathodes, as this could decrease the cost of manufacturing. Turns out, yes you could! This initially made for focusing challenges, but they were eventually solved. The other big development in this new tube was similar to the Chromatron’s wire grille. The Chromatron’s electrically charged wires were altered into what’s called an aperture grille, which was fundamentally similar but didn’t require an electrical charge. The aperture grill was more of a single metal sheet with slits cut vertically through it, though it is sometimes still referred to as being made of wires. The grille separated the color components by blocking their path much like the shadow mask, but kept the vertical phosphor orientation of the chromatron. The aperture grill was very simple and very effective, but perhaps most importantly to Sony’s pocketbook, was unique enough for it to be patented! This new picture tube was called the Trinitron, and it was better than what any of the competition were producing by a wide margin. Introduced in 1968, these televisions were more expensive than the competition, but were universally well received. In fact, Sony received an Emmy award in 1973 for the invention of the Trinitron. But what made the tube so great? Let’s compare a Trinitron tube to a standard shadow mask tube. So, when you put a Trinitron display side-by-side with a conventional shadow-mask display, the most obvious difference is the shape. A Trinitron tube has a distinctive appearance due to the geometry of aperture grille vs. the shadow mask. A shadow mask tube has a near constant curvature across the face because the angles the three electron beams approach at to create the individual Red, Green, and Blue color components need to be consistent across the whole face. The center of the tube is aligned with the electron guns in the back, but the edges need to curve outwards to keep the inside face more or less perpendicular to the source of the beam. A Trinitron tube, meanwhile, only curves side to side. It doesn’t curve vertically, producing a distinctive, cylindrical shape. This is actually a requirement of the aperture grille. The aperture grille is fundamentally simpler than the shadow mask, as it only needs to block the electron beams in the X dimension. Three separate beams arranged in a line can be separated with just a slit. With the green beam in the center, it can pass straight through. But the red and blue beams can only pass through the left, and right, respectively. But this arrangement requires the slits in the grill to always be perpendicular with respect to the three beams’ linear arrangement, in other words the grille had to always stay completely vertical, as any tilt to the left or right could cause cross-over and you’d get messed up colors. We all know from Ghostbusters that you shouldn’t cross the beams! So, Trinitron tubes were designed to only curve in the X dimension, keeping the face of the tube perpendicular to the electron gun along its width, and the beam separation angle constant along its height. The other thing you’ll notice when comparing a Trinitron TV to a conventional one is a generally much brighter image. This was the signature “big deal” of the Trinitron. A shadow mask separates the color components through individual holes in a metal sheet. The earliest CRTs using a shadow mask would lose upwards of 80% of the beam’s energy to the mask itself, with only a paltry percentage actually making it through to excite the phosphors and make the screen glow. This was improved over time through the use of the in-line guns and the triad phosphor arrangement introduced with the Portacolor, but the beam was still blasting its way through tiny slits. This required very powerful electron guns, yet still resulted in a dim picture compared to conventional black and white TVs. The aperture grille, meanwhile, only needs to blocks the beam from left to right to separate the color components. Vertically there is no separation at all, and this allows much more beam energy to pass through it and reach the phosphors. This alone made the phosphors glow more intensely, but the tubes were further helped along by uninterrupted phosphor stripes rather than individual groupings. If you look closely at a Trinitron picture tube, you’ll see continuous lines going from top to bottom with no horizontal separation at all. When operating you see the stripes broken up, but that’s merely the result of the way the image is made via scanning in horizontal lines. As I’ve said now on two separate occasions, phosphor groups you see in a conventional tube ARE NOT pixels. This is analog video we’re talking and any Trinitron display helps to show how this is true by only containing stripes of phosphors. Now do you understand??? Anyway, a conventional tube’s phosphor groupings have black lines above and below each grouping. These lines further reduce the image brightness because, well, they don’t glow. I mean, that’s fairly obvious now isn’t it? But they also cause other problems. Conventional color picture tubes would display false patterns, sometimes injecting color where it shouldn’t be, when displaying an image with fine patterns. This happens when the displayed pattern is misaligned with the phosphor grid. Because a Trinitron doesn’t have a phosphor grid, is was less prone to this occurring, so in many instances a non-trinitron display would produce a Moire pattern or false color, and a Trinitron wouldn’t. Perhaps the only downside to the Trinitron tube is a fine stabilization wire needed to prevent the aperture grille from vibrating. If the tube was exposed to loud sounds, the aperture grille could vibrate and produce wild distortions in color. The stabilization wire would hold them together and prevent this, but the wire itself is visible. On smaller tubes like this only one wire is present, about a third of the way up from the bottom, while larger tubes would have a second wire the same distance from the top. To be fair, these wires are barely visible, since they are much finer than any of the scan lines, but they can be an annoyance when the tube is displaying uniformly bright images. In most cases the image displayed would contain enough variation to make the line essentially invisible. Now, the fact that this stabilization wire was necessary may explain the Chromatron’s ultimate demise. The charged wires probably suffered from the same vibration issues, particularly since they were so far behind the phosphors. And they couldn’t be stabilized as easily as the Trinitron’s aperture grill because a wire holding them all together would remove the required voltage differential between pairs. I’m willing to bet that the Chromatron would have experienced continually worse problems as larger picture tubes were manufactured, and it would have needed even more R&D to address it. The many advantages of the Trinitron picture tube made Sony the undisputed king of televisions (at least from a quality standpoint) for many years, and they were able to charge a premium for their televisions which many people were willing to fork over. These two TVs show how successfully Sony was with the product. These are obviously made many years apart, but the actual picture tube is virtually the same. It might even have the same part number. Sony was able to keep pumping out the same picture tubes, update the cabinets that held them and the electronics that drove them, and they’d still be better than what the competition offered. From 1968 until 1998, any other manufacturer who wanted Trinitron technology in their televisions would need to license it from Sony, and Sony was plenty happy with just making the TVs themselves and made it difficult to do so, though Apple was notably keen on using Trinitron tubes in their early color monitors. However, in 1998 the patent for Trinitron expired, allowing the competition to make their own Trinitron-like picture tubes without paying royalties to Sony. But, the name Trinitron was still a trademark of Sony’s, so they had to fudge the name. Most of these new picture tubes would have some sort of Tron in their title, like Mitsubishi’s Diamondtron. Sony’s timing was pretty good. By the time their patent had expired, LCD and Plasma TVs were beginning to take over. By the mid 2000’s, CRT displays represented a tiny fraction of televisions sold in mainstream markets. But for the entire 30 years that Sony held the patent, it was virtually second to none. Trinitron remained important for many years, and in some applications is still the preferred display device. I’ll tell you that for watching standard definition content, nothing beats it, and that’s why this TV stays here along with my menagerie of obsolete A/V equipment. Thanks for watching, I hope you enjoyed it. If you’re new to this channel, why not hit that Subscribe button? And I suppose I should suggest that you also hit the bell? I hear that’s important. I’d also like to thank all of my Patreon supporters out there. Patreon supporters are allowing me to spend less time in a normal job, and more time making videos for you. If you’re interested in helping out, please check out my Patreon page through the link on your screen or down below in the description. Thanks for your consideration, and I’ll see you next time.



Color television

A 1970s tabletop size Trinitron
A 1970s tabletop size Trinitron

Color television had been studied,[when?] but it was only in the late 1940s that the problem[clarification needed] was seriously considered. At the time, a number of systems were being proposed that used separate red, green and blue signals (RGB), broadcast in succession. Most[which?] systems broadcast entire frames in sequence, with a colored filter (or "gel") that rotated in front of an otherwise conventional black and white television tube.[citation needed] Because they broadcast separate signals for the different colors, all of these systems were incompatible with existing black and white sets. Another problem was that the mechanical filter made them flicker unless very high refresh rates were used. In spite of these problems, the United States Federal Communication Commission selected a sequential-frame 144 frame/s standard from CBS as their color broadcast in 1950.[2]

RCA worked along different lines entirely, using the luminance-chrominance system. This system did not directly encode or transmit the RGB signals; instead it combined these colors into one overall brightness figure, the "luminance". Luminance closely matched the black and white signal of existing broadcasts, allowing it to be displayed on existing televisions. This was a major advantage over the mechanical systems being proposed by other groups. Color information was then separately encoded and folded into the signal as a high-frequency modification to produce a composite video signal – on a black and white television this extra information would be seen as a slight randomization of the image intensity, but the limited resolution of existing sets made this invisible in practice. On color sets the signal would be extracted, decoded back into RGB, and displayed.

Although RCA's system had enormous benefits, it had not been successfully developed because it was difficult to produce the display tubes. Black and white TVs used a continuous signal and the tube could be coated with an even deposit of phosphor. With the compatible color encoding scheme originally developed by Georges Valensi in 1938, the color was changing continually along the line, which was far too fast for any sort of mechanical filter to follow. Instead, the phosphor had to be broken down into a discrete pattern of colored spots. Focusing the right signal on each of these tiny spots was beyond the capability of electron guns of the era, and RCA's early experiments used three-tube projectors, or mirror-based systems known as "Triniscope".[3]

Shadow masks

RCA eventually solved the problem of displaying the color images with their introduction of the shadow mask. The shadow mask consists of a thin sheet of steel with tiny holes photo etched into it, placed just behind the front surface of the picture tube. Three guns, arranged in a triangle, were all aimed at the holes. Stray electrons at the edge of the beam were cut off by the mask, creating a sharply focused spot that was small enough to hit a single colored phosphor on the screen. Since each of the guns was aimed at the hole from a slightly different angle, the spots of phosphor on the tube could be separated slightly to prevent overlap.

The disadvantage of this approach was that for any given amount of gun power, the shadow mask filtered out the majority of the energy. To ensure there was no overlap of the beam on the screen, the dots had to be separated and covered perhaps 25% of its surface.[citation needed] This led to very dim images, requiring much greater electron beam power in order to provide a useful picture. Moreover, the system was highly dependent on the relative angles of the beams between the three guns, which required constant adjustment by the user to ensure the guns hit the correct colors.[citation needed] In spite of this, the technical superiority of the RCA system was overwhelming compared to the CBS system, and was selected as the new NTSC standard in 1953. The first broadcast using the new standard occurred on New Year's Day in 1954, when NBC broadcast the Tournament of Roses Parade.[4]

In spite of this early start, only a few years after regularly scheduled television broadcasting had begun, consumer uptake of color televisions was very slow to start. The dim images, constant adjustments and high costs had kept them in a niche of their own. Low consumer acceptance led to a lack of color programming, further reducing the demand for the sets in a supply and demand problem. In the United States in 1960, only 1 color set was sold for every 50 sets sold in total.[5]


Sony had entered the television market in 1960 with the black and white TV8-301, the first non-projection type all-transistor television.[6] A combination of factors, including its small screen size, limited its sales to niche markets. Sony engineers had been studying the color market, but the situation in Japan was even worse than the U.S.; they accounted for only 300 of the 9 million sets sold that year.[5] But by 1961, dealers were asking the Sony sales department when a color set would be available, and the sales department put pressure on engineering in turn. Masaru Ibuka, Sony's president and co-founder, steadfastly refused to develop a system based on RCA's shadow mask design, which he considered technically deficient. He insisted on developing a unique solution.[7]

In 1961, a Sony delegation was visiting the IEEE trade show in New York City, including Ibuka, Akio Morita (Sony's other co-founder) and Nobutoshi Kihara, who was promoting his new CV-2000 home video tape recorder. This was Kihara's first trip abroad and he spent much of his time wandering the trade floor, where he came across a small booth by the small company Autometric. They were demonstrating a new type of color television based on the Chromatron tube, which used a single electron gun and a vertical grille of electrically charged thin wires instead of a shadow mask. The resulting image was far brighter than anything the RCA design could produce, and lacked the convergence problems that required constant adjustments. He quickly brought Morita and Ibuka to see the design, and Morita was "sold" on the spot.[8]

Sony Chromatron
Sony Chromatron

Morita arranged a deal with Paramount Pictures, who was paying for Chromatic Labs' development of the Chromatron, taking over the entire project. In early 1963, Senri Miyaoka was sent to Manhattan to arrange the transfer of the technology to Sony, which would lead to the closing of Chromatic Labs. He was unimpressed with the labs, describing the windowless basement as "squalor".[8] The American team was only too happy to point out the serious flaws in the Chromatron system, telling Miyaoka that the design was hopeless. By September 1964, a 17-inch prototype had been built in Japan, but mass-production test runs were demonstrating serious problems. Sony engineers were unable to make a version of Chromatron that could be reliably mass-produced.[8]

When sets were finally made available in late 1964, they were put on the market at a competitive 198,000 yen (US$550), but cost the company over 400,000 yen (US$1111.11) to produce. Ibuka had bet the company on Chromatron and had already set up a new factory to produce them with the hopes that the production problems would be ironed out and the line would become profitable. After several thousand sets had shipped, the situation was no better, while Panasonic and Toshiba were in the process of introducing sets based on RCA licenses. By 1966, the Chromatron was breaking the company financially.[9]


The Sony Trinitron logo used from 1992 to the 2000s.
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 phosphors 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.[10]

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 cathodes; this would be more difficult to build, but be lower cost in the long run.[how?] Miyaoka built a prototype and was astonished by how well it worked, although it had focusing problems.[10] Later that week[when?], 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.[11] 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]

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.[11] 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.[12]

Introduction, early models

Officially introduced by Ibuka in April 1968, the original 12 inch Trinitron had a display quality that easily surpassed any commercial set in terms of brightness, color fidelity, and simplicity of operation.[citation needed] The vertical wires in the aperture grille meant that the tube had to be nearly flat vertically; this gave it a unique cylindrical look. It was also all solid state, with the exception of the picture tube itself, which allowed it to be much more compact and cool running than designs like GE's Porta-color. Some larger models such as the KV-1320UB for the United Kingdom market were initially fitted with 3AT2 valves for the extra high tension (high voltage) circuitry, before being redesigned as solid state in the early 70s.

Ibuka ended the press conference by claiming that 10,000 sets would be available by October, well beyond what engineering had told him was possible. Ibuka cajoled Yoshida to take over the effort of bringing the sets into production, and although Yoshida was furious at being put in charge of a task he felt was impossible, he finally accepted the assignment and successfully met the production goal.[13] The KV-1210 was introduced in limited numbers in Japan in October as promised, and in the U.S. as the KV-1210U the following year.

Early color sets intended for the UK market had a PAL decoder that was different from those invented and licensed by Telefunken of Germany, who invented the PAL color system. The decoder inside the UK-sold Sony color Trinitron sets, from the KV-1300UB to the KV-1330UB, had an NTSC decoder adapted for PAL. The decoder used a 64 microsecond delay line to store every other line, but instead of using the delay line to average out the phase of the current line and the previous line, it simply repeated the same line twice.[citation needed] Any phase errors could then be compensated for by using a tint control knob on the front of the set, normally unneeded on a PAL set.


Trinitron computer monitor kx-14cp1
Trinitron computer monitor kx-14cp1

Reviews of the Trinitron were universally positive, although they all mentioned its high cost. Sony won an Emmy Award for the Trinitron in 1973.[14] On his 84th birthday in 1992, Ibuka claimed the Trinitron was his proudest product.

New models quickly followed. Larger sizes at 19" and then 27" were introduced, as well as smaller, including a 7" portable. In the mid-1980s, a new phosphor coating was introduced that was much darker than earlier sets, giving the screens a black color when turned off, as opposed to the earlier light grey. This improved the contrast range of the picture. Early models were generally packaged in silver cases, but with the introduction of the darker screens, Sony also introduced new cases with a dark charcoal color, following a similar change in color taking place in the hi-fi world. This line expanded with 32", 35" and finally 40" units in the 1990s.

In 1980, Sony introduced the "ProFeel" line of prosumer component televisions, consisting of a range of Trinitron monitors that could be connected to standardized tuners. The original lineup consisted of the KX-20xx1 20" and KX-27xx1 27" monitors (the "xx" is an identifier, PS for Europe, HF for Japan, etc.) the VTX-100ES tuner and TXT-100G TeleText decoder. They were often used with a set of SS-X1A stereo speakers, which matched the grey boxy styling of the suite.[15] The concept was to build a market similar to contemporary stereo equipment, where components from different vendors could be mixed to produce a complete system. However, a lack of any major third party components, along with custom connectors between the tuner and monitors, meant that systems mixing fully compatible elements were never effectively realized. They were popular high-end units, however, and found a strong following in production companies where the excellent quality picture made them effective low-cost monitors. A second series of all-black units followed in 1986, the ProFeel Pro, sporting a space-frame around the back of the trapezoidal enclosure that doubled as a carrying handle and holder for the pop-out speakers. These units were paired with the VT-X5R tuner and optionally the APM-X5A speakers.[16]

Sony also produced lines of Trinitron professional studio monitors, the PVM (Professional Video Monitor) and BVM (Broadcast Video Monitor) lines. These models were packaged in grey metal cubes with a variety of inputs that accepted practically any analog format. They originally used tubes similar to the ProFeel line, but over time, they gradually increased in resolution until the late 1990s when they offered over 900 lines. When these were cancelled as part of the wider Trinitron shutdown in 2007, professionals forced Sony to re-open two of the lines to produce the 20 and 14 inch models.[15]

Among similar products, Sony produced the KV-1311 monitor/TV combination. It accepted NTSC-compatible video from various devices as well as analog broadcast TV. Along with its other functions, it had video and audio inputs and outputs as well as a wideband sound-IF decoded output. Its exterior looks much like the monitor illustrated here, with added TV controls.

By this time, Sony was well established as a supplier of reliable equipment; it was preferable to have minimal field failures instead of supporting an extensive service network for the entire United States.

Sony started developing the Trinitron for computer monitor use in the late 1970s. Demand was high, so high that there were examples of third party companies removing Trinitron tubes from televisions to use as monitors. In response, Sony started development of the GDM (Graphic Display Monitor) in 1983, which offered high resolution and faster refresh rates. Sony aggressively promoted the GDM and it became a standard on high-end monitors by the late 1980s. Particularly common models include the Apple Inc. 13" model that was originally sold with the Macintosh II starting in 1987. Well known users also included Digital Equipment Corporation, IBM, Silicon Graphics, Sun Microsystems and others. Demand for a lower cost solution led to the CDP series.[14] In May 1988, the high-end 20 inch DDM model (Data Display Monitor) was introduced with a maximum resolution of 2,048 by 2,048, which went on to be used in the FAA's Advanced Automation System air traffic control system.

These developments meant that Sony was well placed to introduce high-definition televisions (HDTV). In April 1981, they announced the High Definition Video System (HDVS), a suite of MUSE equipment including cameras, recorders, Trinitron monitors and projection TVs.

Sony shipped its 100 millionth Trinitron screen in July 1994, 25 years after it had been introduced. New uses in the computer field and the demand for higher resolution televisions to match the quality of DVD when it was introduced in 1996 led to increased sales, with another 180 million units delivered in the next decade.[17][18]

End of Trinitron

Sony KV-32S42, a typical late-model Trinitron television, manufactured in 2001.
Sony KV-32S42, a typical late-model Trinitron television, manufactured in 2001.
Sony FD Trinitron flat-screen CRT.
Sony FD Trinitron flat-screen CRT.

Sony's patent on the Trinitron display ran out in 1996, after 20 years. After the expiration of Sony's Trinitron patent, manufacturers like Mitsubishi (whose monitor production is now part of NEC Display Solutions) were free to use the Trinitron design for their own product line without license from Sony although they could not use the Trinitron name. For example, Mitsubishi's are called Diamondtron. To some degree, the name Trinitron became a generic term referring to any similar set.

Sony responded with the FD Trinitron, which used computer-controlled feedback systems to ensure sharp focus across a flat screen. Initially introduced on their 27, 32 and 36 inch models in 1998, the new tubes were offered in a variety of resolutions for different uses. The basic WEGA models supported normal 480i signals, but a larger version offered 16:9 aspect ratios. The technology was quickly applied to the entire Trinitron range, from 13 to 36 inch. High resolution versions, Hi-Scan and Super Fine Pitch, were also produced. With the introduction of the FD Trinitron, Sony also introduced a new industrial style, leaving the charcoal colored sets introduced in the 1980s for a new silver styling.

Sony was not the only company producing flat screen CRTs. Other companies had already introduced high-end brands with flat-screen tubes, like Panasonic's Tau. Many other companies entered the market quickly, widely copying the new silver styling as well. The FD Trinitron was unable to regain the cachet that the Trinitron brand had previously possessed; in the 2004 Christmas season, they increased sales by 5%, but only at the cost of a 75% plunge in profits after being forced to lower costs to compete in the market.[19]

At the same time, the introduction of plasma televisions, and then LCD-based ones, led to the high-end market being increasingly focused on the "thin" sets. Both of these technologies have well known problems, and for some time Sony explored a wide array of technologies that would improve upon them in the same way the Trinitron did on the shadow mask. Among these experiments were organic light-emitting diodes (OLED) and the field emission display, but in spite of considerable effort, neither of these technologies matured into competitors. Sony also introduced their Plasmatron displays, and later LCD as well, but these had no inherent technical advantages over similar sets from other companies. From 2006, all of Sony's BRAVIA television products are LCD displays, initially based on screens from Samsung, and later Sharp.[20]

Sony eventually "threw in the towel" on Trinitron, ending production in Japan some time in 2004. In 2006, Sony announced that it would no longer market or sell Trinitrons in the United States or Canada, but continue to sell the Trinitron in China, India, and regions of South America using tubes delivered from their Singapore plant. Production in Singapore finally ended in March 2006, only months after ending production of their rear-projection systems.[18] Two lines of the factory were later brought back online to supply the professional market.


Basic concept

The Trinitron design incorporates two unique features: the single-gun three-cathode picture tube, and the vertically aligned aperture grille.

The single gun consists of a long-necked tube with a single electrode[dubious ] at its base, flaring out into a horizontally-aligned rectangular shape with three vertically-aligned rectangular cathodes inside. Each cathode is fed the amplified signal from one of the decoded RGB signals.

The electrons from the cathodes are all aimed toward a single point at the back of the screen where they hit the aperture grille, a steel sheet[dubious ] with vertical slots cut in it. Due to the slight separation of the cathodes at the back of the tube, the three beams approach the grille at slightly different angles. When they pass through the grille they retain this angle, hitting their individual colored phosphors that are deposited in vertical stripes on the inside of the faceplate. The main purpose of the grille is to ensure that each beam strikes only the phosphor stripes for its color, much as does a shadow mask. However, unlike a shadow mask, there are essentially no obstructions along each entire phosphor stripe. (Larger CRTs have a few horizontal stabilizing wires part way between top and bottom, but in practice, they are not noticed.[dubious ]


In comparison to early shadow mask designs, the Trinitron grille cuts off much less of the signal coming from the electron guns. RCA tubes built in the 1950s cut off about 85% of the electron beam, while the grille cuts off about 25%.[citation needed] Improvements to the shadow mask designs continually narrowed this difference between the two designs, and by the late 1980s the difference in performance, at least theoretically, was eliminated.[citation needed]

Another advantage of the aperture grille was that the distance between the wires remained constant vertically across the screen. In the shadow mask design, the size of the holes in the mask is defined by the required resolution of the phosphor dots on the screen, which was constant. However, the distance from the guns to the holes changed; for dots near the center of the screen, the distance was its shortest, at points in the corners it was at its maximum. To ensure that the guns were focused on the holes, a system known as dynamic convergence had to constantly adjust the focus point as the beam moved across the screen. In the Trinitron design, the problem was greatly simplified,[how?] requiring changes only for large screen sizes, and only on a line-by-line basis.

For this reason, Trinitron systems are easier to focus than shadow masks, and generally had a sharper image.[citation needed] This was a major selling point of the Trinitron design for much of its history. In the 1990s, new computer-controlled real-time feedback focusing systems eliminated this advantage, as well as leading to the introduction of "true flat" designs.


Visible support wires

Even small changes in the alignment of the grille over the phosphors can cause the color purity to shift. Since the wires are thin, small bumps can cause the wires to shift alignment if they are not held in place. Monitors using Trinitron technology have one or more thin tungsten wires running horizontally across the grille to prevent this. Screens 15" and below have one wire located about two thirds of the way down the screen, while monitors greater than 15" have 2 wires at the one-third and two-thirds positions. These wires are less apparent or completely obscured on standard definition sets due to wider scan lines to match the lower resolution of the video being displayed. On computer monitors, where the scan lines are much closer together, the wires are often visible. This is a minor drawback of the Trinitron standard which is not shared by shadow mask CRTs.

Anti-glare coating

This is a polyurethane sheet coated to scatter reflections and can be very easily damaged. The fix is to simply remove the sheet entirely, which one can do on Trinitron and Diamondtron CRT Monitors using a Stanley blade and a chopstick.[21] Many users claim that removal of the anti-glare coating increases the overall light output of the display and results in more vivid colors and a sharper picture, but at the expense of reduced contrast and (as expected) increased reflection from light sources in front of the display screen.[22]

Partial list of other aperture grille brands

See also



  1. ^ "You Guys Can Do It!" Archived 2008-09-22 at the Wayback Machine - Sony Global - Sony History
  2. ^ Ed Reitan, "CBS Field Sequential Color System" Archived 2010-01-05 at the Wayback Machine, 24 August 1997
  3. ^ Ed Reitan, "RCA Dot Sequential Color System" Archived 2010-01-07 at the Wayback Machine, 28 August 1997
  4. ^ Jack Gould, "Television in Review: NBC Color", The New York Times, 4 January 1954
  5. ^ a b Sony, pg. 42
  6. ^ Edward Lucie-Smith, "A History of Industrial Design", Van Nostrand Reinhold, 1983, pg. 208
  7. ^ Sony, pg. 43
  8. ^ a b c Sony, pg. 44
  9. ^ Sony, pg. 45
  10. ^ a b Sony, pg. 46
  11. ^ a b Sony, pg. 47
  12. ^ "Sony Trinitron color television receiver, c 1970" is a common publication claiming that Trinitron and Chromatron are the same. "The History of Television, 1942 to 2000" by Albert Abramson makes the same claim on page 117.
  13. ^ Sony, pg. 48
  14. ^ a b "Sony History" Archived 2009-03-29 at the Wayback Machine
  15. ^ a b "KX-20PS1"
  16. ^ "Sony PROFEEL"
  17. ^ "Sony Pulls Plug on Historic Trinitron TV" Archived 2008-08-21 at the Wayback Machine, IEEE Spectrum Online
  18. ^ a b "Sony to stop making old-style cathode ray tube TVs", Wall Street Journal MarketWatch', 3 March 2008
  19. ^ James Brooke and Saul Hansell, "Samsung Is Now What Sony Once Was", The New York Times, 10 March 2005
  20. ^ Shu-Ching Jean Chen, "Sony Jilts Samsung For Sharp In LCD Panel Production", Forbes, 26 February 2006
  21. ^
  22. ^ "24" Widescreen CRT (FW900) From Ebay arrived, Comments". HardForum. Retrieved 25 November 2012.


  • John Nathan, "Sony: The Private Life", Houghton Mifflin Harcourt, 2001, ISBN 0-618-12694-5

External links

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