Electron beam printer for computer terminal or facsimile - uses magnetic field of impact helicoidal motion to electrons to establish beam direction and to reduce beam divergence

摘要

The printer includes an evacuated enclosure (10) inside which is placed an electron gun emitting a beam of electrons (F). An electron beam deflection controller causes the sweeping of the beam along several windows closed by a plate (1) which is transparent to electrons and which faces a printing surface (3). The printer has in addition focussing coils (30,40,50,60) which create an intense localised magnetic field (H) at the window plate, oriented perpendicularly to the plane of the window so that the electrons acquire a helicoidal movement around the magnetic flux lines, following the flux lines for a short distance. ADVANTAGE - Precise control of divergence of electron beams to give sharper image.