| 摘要 |
<p>PURPOSE:To obtain a small-sized semi-indirectly heated cathode whose necessary electric energy is small and whose electron discharge rise time is short, with respect to a power-saving semi-indirectly heated cathode which is appropriate to the use of an electron view-finder tube. CONSTITUTION:A heater 40 is, in the scope of A, a primary coil where a heater core wire is closely pitch-wound; said wire is closely wound around said heater and further wound in the reverse way to form a triple-layered heat core wire so that the outside diameter may be so sized as to be exactly inserted into the cathode sleeve 20 and welded to said sleeve. One end of the cathode 40 is welded to a tab 5a, but an appropriate tension is applied to said heater, in case of this welding, accordingly the primary coil of the heater 40 becomes concentric with the cathode sleeve 20 in the vicinity coated with thermion emission substance 3 outside the cathode sleeve 20, namely in the scope of C so that said coil may directly face the internal surface of the cathode sleeve 20 without interposing any insulating substance between them.</p> |
