ELECTRODE OF METAL VAPOR DISCHARGE LAMP

摘要

PURPOSE:To prevent a lamp from turning off by providing the winding end of an electrode coil only at the tip end of an electrode axis and generating an arc spot at the tip of the electrode. CONSTITUTION:A two-layer electrode coil 7 consisting of a coarsely wound inside coil 8 and an outside coil 9 which is wound tightly on its outside is wound on the external surface of an electrode axis 6 consisting of a tungusten rod at the tip of the electrode axis 6. Since each winding start end 10a and winding end 10b of the electrode coil 7 is positioned at the tip of the electrode axis 6, an arc spot is generated at start at a stage of a comparatively small potential inclination. As a result, a lamp is prevented from turning off without a sharp rise of re-ignition voltage.