| 摘要 |
PURPOSE:To display clear images by making the luminance of the central area of a diaplay screen higher than that of its peripheral area by using an anode which has an annular shape extending along the inner surface of the glass tube and installing the anode inside the display screen. CONSTITUTION:When a cathode 7 is preheated by feeding a current, electrons are emitted from the preheated cathode 7 into a glass tube 3. The thus emitted electrons are then drawn by an anode 9 installed in the opposite end of a glass tube 3 and move in it, thereby initiating electric discarge between the cathode 7 and the anode 9. The thus initiated electric discharge forms a positive column connecting the cathode 7 and the anode 9 in the glass tube 3. Then ultraviolet raus emitted from the positive column excite a phosphor film 12 formed on the inner surface of the glass tube 3 to emit visible rays which are then irradiated outside the lamp through a convex lens 4. Since the anode 9 has an annular shape extending along the inner surface of the glass tube 3, the positive column becomes adjacent to the phosphor film 12 near the anode 9. Consequently, the phosphor is actively excited and optical emission with high luminance is achieved. |
