Patent ID: 7592742

Claim:
A bulb-shaped fluorescent lamp comprising: (A) a fluorescent lamp comprising: (A-1) a light-emitting tube, (A-2) a main amalgam contained in a thin pipe sealed at one end of the light-emitting tube so as to protrude into the light emitting tube, wherein the main amalgam provides a mercury-vapor pressure of 0.04 Pa or more at 25° C., and (A-3) an auxiliary amalgam provided in the vicinity of a pair of electrodes sealed to the light-emitting tube, wherein the auxiliary amalgam comprises: (A-3-1) a base containing at least one element selected from the group consisting of chromium, molybdenum and tungsten, (A-3-2) a metal layer provided on the base, the metal layer consisting mainly of one element selected from the group consisting of gold, silver, palladium, platinum, lead, tin, zinc and bismuth, or consisting mainly of alloy that contains at least two elements selected from the group consisting of gold, silver, palladium, platinum, lead, tin, zinc and bismuth, and having a thickness of 0.05 μm to 5 μm, wherein crystals constituting the metal layer are porous and satisfy at least one of following three conditions: randomly selected regions of the surface of the metal layer have an arithmetic mean roughness exceeding 0.02 μm; the metal layer has a maximum roughness-height Ry that exceeds 0.3 μm; and the surface of the metal layer has a ten-point average roughness exceeding 0.2 μm, and (A-3-3) a diffusion-inhibiting layer provided between the base and the metal layer and having a thickness of 0.01 μm to 5 μm, wherein the diffusion-inhibiting layer is made mainly of one element selected from the group consisting of nickel, chromium, molybdenum and tungsten, and inhibits the diffusion of metal from the metal layer in to the base; (B) a lamp-driving device having a substrate and electronic components mounted on the substrate and configured to output high-frequency power to the fluorescent lamp; and (C) a cover containing the lamp-driving device and having a cap at one end and a holding part at the other end, the holding part holding the fluorescent lamp.