Beam-index tube
The beam-index tube is a color television cathode ray tube (CRT) design, using phosphor stripes and active-feedback timing, rather than phosphor dots and a beam-shadowing mask as developed by RCA. Beam indexing offered much brighter pictures than shadow-mask CRTs, reducing power consumption, and as they used a single electron gun rather than three, they were easier to build and required no alignment adjustments. Philco led the development of the beam-indexing concept in a series of experimental devices they called the Apple tube.