Chromatron
Early 1950s had brought a compatible electronic color television system to series production, with the aid of a shadow mask CRT could play useful color images in exploiting the normal black and white video bandwidth, the Radio Corporation of America (RCA). Three electron beams were modulated with the color video signals, the shadow mask with one hole for a behind befindliches color triad on the screen caused by mechanical means, that the transmitted with a different incidence angle electron met belonging to them color phosphor. The time used 15 -inch color picture tube 15GP22 reached a maximum deflection angle of 45 ° for the image width. Extensive convergence correction circuits were needed to enable the three color images came on the screen to cover. The phosphors were so faint that you had to darken the room for color television. In addition, a good 80 % of the beam power absorbed by the shadow mask and converted into heat.
Ernest O. Lawrence developed from 1951 Chromatron color picture tube, which should get along with improved brightness compared to the shadow mask CRT with only one electron gun instead of three electron guns. The screen displays the three phosphors for the primary colors red, green and blue were fitted in place of color triads in the form of vertical streaks. Behind the streaks on the inside of the tube fine vertical wires were attached, which diverted by means of an electrical control pulse to the electron beam to the static red, green or blue phosphor. Since only one electron beam was used for the three primary colors were also the elaborate convergence circuits as the shadow mask picture tube gone, and the tube was able to work with a larger deflection angle of 72 ° ( instead of 45 ° as in the first shadow mask CRT).
However, the technicians were given the associated problems not to grips with the fine wire filaments before the screen could not be sufficiently stable held in position, the high driving voltages up to 8 kV led to flashover in the picture tube, so that it never for mass production came.
The Japanese company Sony experimented in the 1960s at great expense to the chromatron finally broke away from the idea, but developed it based the Trinitron picture tube that although the light strip and the fine vertical wires took over from the Chromatron instead of a shadow mask, but nevertheless with three separate cathodes, but now worked in an electron system for the three primary colors.