| 摘要 |
PURPOSE:To obtain a display unit being selectively illuminated and to plan to make the unit thin and compact by a method wherein, regarding the fluorescent display unit used to select and illuminate groups of anodes and cathodes arranged crosswise in the form of a matrix, a diode is composed of the anode provided with a fluorescent layer and the cathode with thermions only without a grid. CONSTITUTION:To carry out preheating at less than 400 deg.C, a cathode-preheating supply source 20 and the cathode 15 are connected together through a switching circuit 21 whenever the input of a display signal is not applied, in order to allow the preheating current to flow. When the input of the display signal is applied, the switching circuit 21 operates to switch the preheating supply over to a cathode ignition supply 22. As a result, the cathode-heating current increases and electrons are discharged from the thermion discharging material of the cathode. The electrons discharged are accelerated toward the anode which positive voltage has been applied, causing a fluorescent layer 13a at the intersecting point of the anode and cathode. In other words, the make and break of the above switching circuits 18, 21 make the dotted fluorescent layer of the anode 12 arranged in the shape of a matrix operate and illuminate selectively. |
