| 摘要 |
PURPOSE:To obtain a discharge lamp whose electrodes have good electron radiation ability and which exhibits little deterioration in the luminous flux and enjoys a long service lifetime, by providing electrodes each having an electron radiation substance which contains yttrium oxide and lanthanum oxide and limiting the actuation temperature of the electrode to a specific range. CONSTITUTION:A luminous tube 1 is provided with electrodes 2a, 2b, each having an electron radiation substance 18 which contains yttrium oxide and lanthanum oxide. The actuation temperature of the electrodes 2a, 2b are limited to 1,300- 1,900 deg.C. Each electrode is prepared, for example, by immersing an electrode-forming member which consists of a tungsten rod 15 and tungesten wires 16, 17 wound thereon in a suspension, which was prepared by adding a mixture consisting 80mol% of Y2O3 and 20mol% of La2O3 to butyl acetate together with nitro cellulose lacquer, pulling the electrode-forming member out of the suspension and then heating it in an argon gas atmosphere at 1,800 deg.C. A luminous tube 1 equipped with the thus-formed electrodes 2a, 2b and filled with a suitable amount of each of mercury, argon gas and the iodides of Sc and/or Na is disposed in an outer tube 14. A discharge lamp is formed so as to make the actuation temperatures of the electrodes 2a, 2b become about 1,600 deg.C during its lighting. |
