Cathode ray tube used as light source

摘要

The disclosed cathode ray tube for use as a light source has an electron gun including a first, a second and third grid electrodes similar to conventional three electrode electron guns but the axial length of the second grid electrode is adjusted to form a bipotential electron lens with the third grid electrode. An electron beam emitted from a cathode electrode is focussed by the electron lens and then diverged until it reaches an associated phosphor screen. The phosphor screen is luminesced with a desired diameter by the diverged electron beam.