Abstract: A pulse of current of several hundreds of volts is established between two electrodes immersed in a resistive liquid. By concentration of the current at the end of one electrode, which is bonded onto an insulating support, a volume of liquid in contact with the end of this electrode is vaporised, causing an abrupt drop in current. Because of the voltage of the pulse, which is several hundred volts, a greater current re-establishes itself immediately across the volume of vaporised liquid, as a result of a sort of ionization of the vapor, causing superheating and energy sufficient to expel a droplet of liquid through an opening provided in a membrane. In order to limit the energy of the superheating phase and control the size of the droplets, the current of the energizing pulse is limited.

Abstract: The printer comprises a series of needles (1) each associated to an electric lead (8) which extends in the gap of a permanent magnet (11). The extremities of each lead are fixed to respective supports (9,10) and are selectively connected to a current source to make a current (I) circulate in said leads so that, in the presence of a magnetic field in the air gap, a force (F) acts upon the lead (8) which communicates to the needle (I) an elongation (e) in the direction of the surface to be printed.

Abstract: The needles (1) of this printer are fed by an electrical conductor (10) associated with the secondary of a step-down transformer (9) connected to a current pulse generator (8). The needle (1) having been placed in the magnetic field of a permanent magnet (7), the current (I) which passes through the needle gives rise to forces which tend to restore this needle to a straight line joining its points of support and guidance (2,3) while displacing the free end against a writing support.

Abstract: A video cathode tube having a matrix of low emission threshold field effect emitters oriented to emit toward a luminescent layer. A first system of mutually insulated conductive paths is arranged along rows of emitters with the emitters in any row electrically connected to a corresponding conductive path of the first system. A second system of mutually insulated conductive paths is disposed in contact with the luminescent layer and extends in front of columns of the emitters. A first bank of contacts individually connected to respective conductive paths of the first system are sequentially energized to a first potential, and a second bank of contacts individually connected to respective conductive paths of the second system are sequentially energized to a second potential. A control grid connectable to a voltage source is interposed between the matrix of emitters and the second system of conductive paths.