Electron gun having a main lens

Abstract

An electron gun of the in line type comprises cathodes (2) for emitting electrons, the cathodes being juxtaposed in a first direction. The electron gun comprises a main lens section (4) for focusing the beams of electrons onto a display screen (36). Conventionally, the electrodes (20, 21, 22) of the main lens section comprise a base plate (23), which is a plate shaped element provided with separate apertures for each of the beams. According to the invention, at least one of the electrodes (10, 11, 12) of the main lens section is provided with a so called field cutter (14, 19), which is a plate shaped element provided with a common aperture for all beams. The field cutter allows in preferred embodiments to have astigmatic main lenses that result in better spot performance and a reduced horizontal magnification. Preferably, the main lens has positive dynamic astigmatism, so that a separate DAF section is no longer required.

Dependencies are inferred from the claim text.