| 摘要 |
PURPOSE:To remove the density difference of a mercury atom and improve the luminous efficiency of a low pressure mercury vapor discharge lamp by providing a cathode in an inner tube and an anode at the space between the inner and an outer tube and installing amalgam that controls the mercury vapor pressure, near the anode. CONSTITUTION:A direct tube type inner tube 5 with small diameter is housed in an outer tube 1 having a spherical section 3, one end is sealed with a stem 2, the other end is opened in the outer tube 1, a discharge space 4 is formed, and the inner surface of the outer tube 1 and the inner and outer surfaces of the inner tube 5 are coated with a phosphor coat 6. In addition, a coil filament type preheating cathode 8 is provided at the bottom of the inner tube 5 and an anode 10 is provided at the bottom of the space section 9 between the outer and inner tubes 1 and 5, then amalgam 13 that controls the mercury vapor pressure is installed in an exhaust tube 12 provided near the anode 10. As a result, for the DC lighting, the density difference of a mercury atom generated at the space section 9 due to a cataphoresis phenomenon can be removed and luminous efficiency can be improved. |
