A type of cathode-ray tube designed to produce the coloured image in colour television. The coloured image is produced by varying the intensity of excitation of three different phosphors that produce the three primary colours red, green, and blue and reproduce the original colours of the image by an additive colour process.

The three-gun colour picture tube consists of a configuration of three electron guns, the red gun, blue gun, and green gun, that are tilted slightly so that the electron beams intersect just in front of the screen. Each electron beam has an individual electron lens system of focusing and is directed towards one of the three sets of colour phosphors. There are several different types of colour picture tube, the main differences being in the configuration of electron guns and arrangement of the phosphors on the screen.