| 摘要 |
PURPOSE:To maintain the internal atmosphere of the airtight case at a high level vacuum so as to prevent any deterioration of the luminance of a fluorescent character display tube by absorbing the residual gas existing in the case by active alumina placed in at least a part of the case. CONSTITUTION:In a fluorescent character display tube, electrons discharged from a cathode 29 reach an anode 25 after passing through a mesh-like control electrode 28 and a part of the electrons stimulate a phosphor 26 to cause it to emit light. When making such a fluorescent character display tube, an anode feeder 22 is printed on a base plate 21 by silver wiring before a black insulating layer 24 is formed on the anode feeder 22. Next, an anode 25 is formed on the back insulating layer 24. At the same time, a mixture solution composed of 10wt% of active alumina and 90wt% of 3% dilute acetic acid is applied to the surface of the insulating layer 24 by spraying to form an active alumina layer 27. As a result, it is possible to maintain a high level vacuum by absorbing the residual gas existing in a vacuum case by active alumina. Accordingly, it is possible to extend the life of the display tube by preventing any deterioration of its luminance. |
