FLAT THIN CRT BASED ON CONTROLLED ELECTRON-TRANSPORT THROUGH INSULATING STRUCTURES

The feasibility is demonstrated of a flat thin cathode ray tube with i nsulating supports inside the envelope to withstand the atmospheric pr essure. The supports are actively used to guide the electrons from the cathodes to the phosphor screen. The electrons are transported throug h the insulating structures by a self-regulating secondary emission pr ocess, provided a sufficiently high voltage is applied between the ent rance and the exit of the structures. The local potentials are automat ically adjusted by charge deposition on the insulating walls until a s ituation is established characterized by the property that the local a verage secondary emission coefficient is equal to one everywhere in th e structure. The flat thin CRT with these insulating internal supports has a thickness of about 1 cm for any display size and a relatively l ow mass. Large displays have been realized showing a good performance: brightness, contrast, colour purity and power dissipation are compara ble to or better than obtained with conventional cathode ray tubes. So me other interesting applications based on the same phenomenon are bri efly discussed: an electron 'fibre', an electron source with high curr ent density and a beam switch.