Trinitron was Sony's brand name for its line of aperture-grille-based CRTs used in television sets and computer monitors. It was one of the first television systems to enter the market since the 1950s. 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.

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.

Color television had been demonstrable since the 1920s starting with John Logie Baird's system. In the late 1940s it was perfected by both CBS and RCA. At the time, a number of systems were being proposed that used separate red, green and blue signals (RGB), broadcast in succession. Most 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 Communications Commission selected a sequential-frame 144 frame/s standard from CBS as their color broadcast in 1950.

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 proper 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".

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.